API: Rolling daily sum resets rolling sum when calculated on an hourly timestamp indexed dataframe
#### Code Sample, a copy-pastable example if possible

```python
import numpy as np
import pandas as pd

data = np.random.randint(1,10,520)
index = pd.date_range('2013-01-01 09:00:00','2013-04-01 16:00:00', freq='BH')
df = pd.DataFrame(data, index=index, columns=['trips'])

df.rolling('2D').sum()
```

## Expected results

<details>

```
rec.array([('2013-01-01 09:00:00',   3.,  3,  nan),
           ('2013-01-01 10:00:00',   9., 12,  nan),
           ('2013-01-01 11:00:00',   1., 13,  nan),
           ('2013-01-01 12:00:00',   7., 20,  nan),
           ('2013-01-01 13:00:00',   8., 28,  nan),
           ('2013-01-01 14:00:00',  nan, 28,  nan),
           ('2013-01-01 15:00:00',   3., 31,  nan),
           ('2013-01-01 16:00:00',   6., 37,  nan),
           ('2013-01-02 09:00:00',   2., 39,  nan),
           ('2013-01-02 10:00:00',  nan, 39,  nan),
           ('2013-01-02 11:00:00',   7., 46,  nan),
           ('2013-01-02 12:00:00',   3., 49,  nan),
           ('2013-01-02 13:00:00',   7., 56,  nan),
           ('2013-01-02 14:00:00',   7., 63,  nan),
           ('2013-01-02 15:00:00',   2., 65,  nan),
           ('2013-01-02 16:00:00',   4., 69,  69.),
           ('2013-01-03 09:00:00',   1., 67,  67.),
           ('2013-01-03 10:00:00',   1., 59,  59.),
           ('2013-01-03 11:00:00',   5., 63,  63.),
           ('2013-01-03 12:00:00',  nan, 56,  56.),
           ('2013-01-03 13:00:00',   7., 55,  55.),
           ('2013-01-03 14:00:00',   4., 59,  59.),
           ('2013-01-03 15:00:00',  nan, 56,  56.),
           ('2013-01-03 16:00:00',   5., 55,  55.),
           ('2013-01-04 09:00:00',   5., 58,  58.),
           ('2013-01-04 10:00:00',   9., 67,  67.),
           ('2013-01-04 11:00:00',   1., 61,  61.),
           ('2013-01-04 12:00:00',   1., 59,  59.),
           ('2013-01-04 13:00:00',   9., 61,  61.),
           ('2013-01-04 14:00:00',   2., 56,  56.),
           ('2013-01-04 15:00:00',  nan, 54,  54.),
           ('2013-01-04 16:00:00',   9., 59,  59.),
           ('2013-01-07 09:00:00',   5.,  5,  63.),
           ('2013-01-07 10:00:00',   3.,  8,  65.),
           ('2013-01-07 11:00:00',   2., 10,  62.),
           ('2013-01-07 12:00:00',   9., 19,  71.),
           ('2013-01-07 13:00:00',   7., 26,  71.),
           ('2013-01-07 14:00:00',   1., 27,  68.),
           ('2013-01-07 15:00:00',   9., 36,  77.),
           ('2013-01-07 16:00:00',   7., 43,  79.),
           ('2013-01-08 09:00:00',   4., 47,  78.),
           ('2013-01-08 10:00:00',   5., 52,  74.),
           ('2013-01-08 11:00:00',   5., 57,  78.),
           ('2013-01-08 12:00:00',   9., 66,  86.),
           ('2013-01-08 13:00:00',   5., 71,  82.),
           ('2013-01-08 14:00:00',   7., 78,  87.),
           ('2013-01-08 15:00:00',   5., 83,  92.),
           ('2013-01-08 16:00:00',   3., 86,  86.),
           ('2013-01-09 09:00:00',   7., 88,  88.),
           ('2013-01-09 10:00:00',   9., 94,  94.),
           ('2013-01-09 11:00:00',   2., 94,  94.),
           ('2013-01-09 12:00:00',   6., 91,  91.),
           ('2013-01-09 13:00:00',   9., 93,  93.),
           ('2013-01-09 14:00:00',   5., 97,  97.),
           ('2013-01-09 15:00:00',   6., 94,  94.),
           ('2013-01-09 16:00:00',   2., 89,  89.),
           ('2013-01-10 09:00:00',   5., 90,  90.),
           ('2013-01-10 10:00:00',   5., 90,  90.),
           ('2013-01-10 11:00:00',  nan, 85,  85.),
           ('2013-01-10 12:00:00',   6., 82,  82.),
           ('2013-01-10 13:00:00',  nan, 77,  77.),
           ('2013-01-10 14:00:00',   5., 75,  75.),
           ('2013-01-10 15:00:00',   1., 71,  71.),
           ('2013-01-10 16:00:00',   7., 75,  75.),
           ('2013-01-11 09:00:00',   2., 70,  70.),
           ('2013-01-11 10:00:00',   5., 66,  66.),
           ('2013-01-11 11:00:00',   4., 68,  68.),
           ('2013-01-11 12:00:00',   6., 68,  68.),
           ('2013-01-11 13:00:00',   4., 63,  63.),
           ('2013-01-11 14:00:00',   2., 60,  60.),
           ('2013-01-11 15:00:00',   6., 60,  60.),
           ('2013-01-11 16:00:00',   2., 60,  60.),
           ('2013-01-14 09:00:00',   5.,  5,  60.),
           ('2013-01-14 10:00:00',   5., 10,  60.),
           ('2013-01-14 11:00:00',   4., 14,  64.),
           ('2013-01-14 12:00:00',   8., 22,  66.),
           ('2013-01-14 13:00:00',   2., 24,  68.),
           ('2013-01-14 14:00:00',   4., 28,  67.),
           ('2013-01-14 15:00:00',   2., 30,  68.),
           ('2013-01-14 16:00:00',   1., 31,  62.),
           ('2013-01-15 09:00:00',   3., 34,  63.),
           ('2013-01-15 10:00:00',   7., 41,  65.),
           ('2013-01-15 11:00:00',  nan, 41,  61.),
           ('2013-01-15 12:00:00',   9., 50,  64.),
           ('2013-01-15 13:00:00',   4., 54,  64.),
           ('2013-01-15 14:00:00',   5., 59,  67.),
           ('2013-01-15 15:00:00',   7., 66,  68.),
           ('2013-01-15 16:00:00',   8., 74,  74.),
           ('2013-01-16 09:00:00',   3., 72,  72.),
           ('2013-01-16 10:00:00',   5., 72,  72.),
           ('2013-01-16 11:00:00',  nan, 68,  68.),
           ('2013-01-16 12:00:00',   2., 62,  62.),
           ('2013-01-16 13:00:00',  nan, 60,  60.),
           ('2013-01-16 14:00:00',   2., 58,  58.),
           ('2013-01-16 15:00:00',   9., 65,  65.),
           ('2013-01-16 16:00:00',  nan, 64,  64.),
           ('2013-01-17 09:00:00',   1., 62,  62.),
           ('2013-01-17 10:00:00',   5., 60,  60.),
           ('2013-01-17 11:00:00',   2., 62,  62.),
           ('2013-01-17 12:00:00',   3., 56,  56.),
           ('2013-01-17 13:00:00',   3., 55,  55.),
           ('2013-01-17 14:00:00',   8., 58,  58.),
           ('2013-01-17 15:00:00',   1., 52,  52.),
           ('2013-01-17 16:00:00',  nan, 44,  44.),
           ('2013-01-18 09:00:00',   6., 47,  47.),
           ('2013-01-18 10:00:00',   6., 48,  48.),
           ('2013-01-18 11:00:00',   8., 56,  56.),
           ('2013-01-18 12:00:00',   2., 56,  56.),
           ('2013-01-18 13:00:00',   2., 58,  58.),
           ('2013-01-18 14:00:00',  nan, 56,  56.),
           ('2013-01-18 15:00:00',   2., 49,  49.),
           ('2013-01-18 16:00:00',   1., 50,  50.),
           ('2013-01-21 09:00:00',   3.,  3,  52.),
           ('2013-01-21 10:00:00',   3.,  6,  50.),
           ('2013-01-21 11:00:00',   1.,  7,  49.),
           ('2013-01-21 12:00:00',   8., 15,  54.),
           ('2013-01-21 13:00:00',   9., 24,  60.),
           ('2013-01-21 14:00:00',   8., 32,  60.),
           ('2013-01-21 15:00:00',   1., 33,  60.),
           ('2013-01-21 16:00:00',   1., 34,  61.),
           ('2013-01-22 09:00:00',   3., 37,  58.),
           ('2013-01-22 10:00:00',   6., 43,  58.),
           ('2013-01-22 11:00:00',   4., 47,  54.),
           ('2013-01-22 12:00:00',  nan, 47,  52.),
           ('2013-01-22 13:00:00',   6., 53,  56.),
           ('2013-01-22 14:00:00',   6., 59,  62.),
           ('2013-01-22 15:00:00',   7., 66,  67.),
           ('2013-01-22 16:00:00',   3., 69,  69.),
           ('2013-01-23 09:00:00',   6., 72,  72.),
           ('2013-01-23 10:00:00',   1., 70,  70.),
           ('2013-01-23 11:00:00',   5., 74,  74.),
           ('2013-01-23 12:00:00',   5., 71,  71.),
           ('2013-01-23 13:00:00',   2., 64,  64.),
           ('2013-01-23 14:00:00',   1., 57,  57.),
           ('2013-01-23 15:00:00',   4., 60,  60.),
           ('2013-01-23 16:00:00',   2., 61,  61.),
           ('2013-01-24 09:00:00',   1., 59,  59.),
           ('2013-01-24 10:00:00',   3., 56,  56.),
           ('2013-01-24 11:00:00',   1., 53,  53.),
           ('2013-01-24 12:00:00',   2., 55,  55.),
           ('2013-01-24 13:00:00',   8., 57,  57.),
           ('2013-01-24 14:00:00',   3., 54,  54.),
           ('2013-01-24 15:00:00',   9., 56,  56.),
           ('2013-01-24 16:00:00',   9., 62,  62.),
           ('2013-01-25 09:00:00',   2., 58,  58.),
           ('2013-01-25 10:00:00',   7., 64,  64.),
           ('2013-01-25 11:00:00',   9., 68,  68.),
           ('2013-01-25 12:00:00',   8., 71,  71.),
           ('2013-01-25 13:00:00',   6., 75,  75.),
           ('2013-01-25 14:00:00',   5., 79,  79.),
           ('2013-01-25 15:00:00',   3., 78,  78.),
           ('2013-01-25 16:00:00',  nan, 76,  76.),
           ('2013-01-28 09:00:00',   6.,  6,  81.),
           ('2013-01-28 10:00:00',   2.,  8,  80.),
           ('2013-01-28 11:00:00',   6., 14,  85.),
           ('2013-01-28 12:00:00',   4., 18,  87.),
           ('2013-01-28 13:00:00',   4., 22,  83.),
           ('2013-01-28 14:00:00',   9., 31,  89.),
           ('2013-01-28 15:00:00',   3., 34,  83.),
           ('2013-01-28 16:00:00',   3., 37,  77.),
           ('2013-01-29 09:00:00',   2., 39,  77.),
           ('2013-01-29 10:00:00',   2., 41,  72.),
           ('2013-01-29 11:00:00',   4., 45,  67.),
           ('2013-01-29 12:00:00',   7., 52,  66.),
           ('2013-01-29 13:00:00',   2., 54,  62.),
           ('2013-01-29 14:00:00',   7., 61,  64.),
           ('2013-01-29 15:00:00',   7., 68,  68.),
           ('2013-01-29 16:00:00',   7., 75,  75.),
           ('2013-01-30 09:00:00',   4., 73,  73.),
           ('2013-01-30 10:00:00',   8., 79,  79.),
           ('2013-01-30 11:00:00',  nan, 73,  73.),
           ('2013-01-30 12:00:00',   3., 72,  72.),
           ('2013-01-30 13:00:00',   9., 77,  77.),
           ('2013-01-30 14:00:00',   8., 76,  76.),
           ('2013-01-30 15:00:00',   1., 74,  74.),
           ('2013-01-30 16:00:00',   7., 78,  78.),
           ('2013-01-31 09:00:00',   9., 85,  85.),
           ('2013-01-31 10:00:00',   2., 85,  85.),
           ('2013-01-31 11:00:00',  nan, 81,  81.),
           ('2013-01-31 12:00:00',  nan, 74,  74.),
           ('2013-01-31 13:00:00',   4., 76,  76.),
           ('2013-01-31 14:00:00',   7., 76,  76.),
           ('2013-01-31 15:00:00',   8., 77,  77.),
           ('2013-01-31 16:00:00',   5., 75,  75.),
           ('2013-02-01 09:00:00',   3., 74,  74.),
           ('2013-02-01 10:00:00',   5., 71,  71.),
           ('2013-02-01 11:00:00',  nan, 71,  71.),
           ('2013-02-01 12:00:00',   4., 72,  72.),
           ('2013-02-01 13:00:00',   6., 69,  69.),
           ('2013-02-01 14:00:00',   9., 70,  70.),
           ('2013-02-01 15:00:00',   7., 76,  76.),
           ('2013-02-01 16:00:00',   9., 78,  78.),
           ('2013-02-04 09:00:00',   6.,  6,  75.),
           ('2013-02-04 10:00:00',   2.,  8,  75.),
           ('2013-02-04 11:00:00',   6., 14,  81.),
           ('2013-02-04 12:00:00',   2., 16,  83.),
           ('2013-02-04 13:00:00',   7., 23,  86.),
           ('2013-02-04 14:00:00',   5., 28,  84.),
           ('2013-02-04 15:00:00',  nan, 28,  76.),
           ('2013-02-04 16:00:00',   2., 30,  73.),
           ('2013-02-05 09:00:00',   4., 34,  74.),
           ('2013-02-05 10:00:00',   1., 35,  70.),
           ('2013-02-05 11:00:00',   9., 44,  79.),
           ('2013-02-05 12:00:00',   4., 48,  79.),
           ('2013-02-05 13:00:00',   5., 53,  78.),
           ('2013-02-05 14:00:00',   4., 57,  73.),
           ('2013-02-05 15:00:00',   5., 62,  71.),
           ('2013-02-05 16:00:00',   3., 65,  65.),
           ('2013-02-06 09:00:00',   6., 65,  65.),
           ('2013-02-06 10:00:00',   8., 71,  71.),
           ('2013-02-06 11:00:00',   2., 67,  67.),
           ('2013-02-06 12:00:00',   5., 70,  70.),
           ('2013-02-06 13:00:00',   9., 72,  72.),
           ('2013-02-06 14:00:00',  nan, 67,  67.),
           ('2013-02-06 15:00:00',   8., 75,  75.),
           ('2013-02-06 16:00:00',   9., 82,  82.),
           ('2013-02-07 09:00:00',   9., 87,  87.),
           ('2013-02-07 10:00:00',   9., 95,  95.),
           ('2013-02-07 11:00:00',   8., 94,  94.),
           ('2013-02-07 12:00:00',   3., 93,  93.),
           ('2013-02-07 13:00:00',  nan, 88,  88.),
           ('2013-02-07 14:00:00',   1., 85,  85.),
           ('2013-02-07 15:00:00',   5., 85,  85.),
           ('2013-02-07 16:00:00',   7., 89,  89.),
           ('2013-02-08 09:00:00',   9., 92,  92.),
           ('2013-02-08 10:00:00',   1., 85,  85.),
           ('2013-02-08 11:00:00',   7., 90,  90.),
           ('2013-02-08 12:00:00',   6., 91,  91.),
           ('2013-02-08 13:00:00',   9., 91,  91.),
           ('2013-02-08 14:00:00',   4., 95,  95.),
           ('2013-02-08 15:00:00',   6., 93,  93.),
           ('2013-02-08 16:00:00',   4., 88,  88.),
           ('2013-02-11 09:00:00',   7.,  7,  86.),
           ('2013-02-11 10:00:00',   9., 16,  86.),
           ('2013-02-11 11:00:00',  nan, 16,  78.),
           ('2013-02-11 12:00:00',   9., 25,  84.),
           ('2013-02-11 13:00:00',   2., 27,  86.),
           ('2013-02-11 14:00:00',   2., 29,  87.),
           ('2013-02-11 15:00:00',   1., 30,  83.),
           ('2013-02-11 16:00:00',  nan, 30,  76.),
           ('2013-02-12 09:00:00',   7., 37,  74.),
           ('2013-02-12 10:00:00',   9., 46,  82.),
           ('2013-02-12 11:00:00',   1., 47,  76.),
           ('2013-02-12 12:00:00',  nan, 47,  70.),
           ('2013-02-12 13:00:00',   2., 49,  63.),
           ('2013-02-12 14:00:00',   8., 57,  67.),
           ('2013-02-12 15:00:00',   7., 64,  68.),
           ('2013-02-12 16:00:00',   7., 71,  71.),
           ('2013-02-13 09:00:00',   3., 67,  67.),
           ('2013-02-13 10:00:00',  nan, 58,  58.),
           ('2013-02-13 11:00:00',   4., 62,  62.),
           ('2013-02-13 12:00:00',   3., 56,  56.),
           ('2013-02-13 13:00:00',   5., 59,  59.),
           ('2013-02-13 14:00:00',   4., 61,  61.),
           ('2013-02-13 15:00:00',   3., 63,  63.),
           ('2013-02-13 16:00:00',   3., 66,  66.),
           ('2013-02-14 09:00:00',   3., 62,  62.),
           ('2013-02-14 10:00:00',   9., 62,  62.),
           ('2013-02-14 11:00:00',   9., 70,  70.),
           ('2013-02-14 12:00:00',  nan, 70,  70.),
           ('2013-02-14 13:00:00',   7., 75,  75.),
           ('2013-02-14 14:00:00',   7., 74,  74.),
           ('2013-02-14 15:00:00',   5., 72,  72.),
           ('2013-02-14 16:00:00',   6., 71,  71.),
           ('2013-02-15 09:00:00',   4., 72,  72.),
           ('2013-02-15 10:00:00',   3., 75,  75.),
           ('2013-02-15 11:00:00',   8., 79,  79.),
           ('2013-02-15 12:00:00',   1., 77,  77.),
           ('2013-02-15 13:00:00',   5., 77,  77.),
           ('2013-02-15 14:00:00',   5., 78,  78.),
           ('2013-02-15 15:00:00',   2., 77,  77.),
           ('2013-02-15 16:00:00',   3., 77,  77.),
           ('2013-02-18 09:00:00',   2.,  2,  76.),
           ('2013-02-18 10:00:00',   8., 10,  75.),
           ('2013-02-18 11:00:00',   9., 19,  75.),
           ('2013-02-18 12:00:00',   9., 28,  84.),
           ('2013-02-18 13:00:00',   7., 35,  84.),
           ('2013-02-18 14:00:00',   5., 40,  82.),
           ('2013-02-18 15:00:00',   5., 45,  82.),
           ('2013-02-18 16:00:00',   8., 53,  84.),
           ('2013-02-19 09:00:00',   5., 58,  85.),
           ('2013-02-19 10:00:00',   1., 59,  83.),
           ('2013-02-19 11:00:00',   3., 62,  78.),
           ('2013-02-19 12:00:00',   7., 69,  84.),
           ('2013-02-19 13:00:00',   5., 74,  84.),
           ('2013-02-19 14:00:00',   5., 79,  84.),
           ('2013-02-19 15:00:00',   3., 82,  85.),
           ('2013-02-19 16:00:00',   4., 86,  86.),
           ('2013-02-20 09:00:00',   5., 89,  89.),
           ('2013-02-20 10:00:00',   4., 85,  85.),
           ('2013-02-20 11:00:00',   5., 81,  81.),
           ('2013-02-20 12:00:00',   2., 74,  74.),
           ('2013-02-20 13:00:00',   8., 75,  75.),
           ('2013-02-20 14:00:00',   3., 73,  73.),
           ('2013-02-20 15:00:00',   3., 71,  71.),
           ('2013-02-20 16:00:00',   8., 71,  71.),
           ('2013-02-21 09:00:00',   4., 70,  70.),
           ('2013-02-21 10:00:00',   5., 74,  74.),
           ('2013-02-21 11:00:00',   1., 72,  72.),
           ('2013-02-21 12:00:00',   2., 67,  67.),
           ('2013-02-21 13:00:00',   5., 67,  67.),
           ('2013-02-21 14:00:00',   6., 68,  68.),
           ('2013-02-21 15:00:00',   1., 66,  66.),
           ('2013-02-21 16:00:00',   8., 70,  70.),
           ('2013-02-22 09:00:00',   5., 70,  70.),
           ('2013-02-22 10:00:00',   2., 68,  68.),
           ('2013-02-22 11:00:00',   5., 68,  68.),
           ('2013-02-22 12:00:00',   5., 71,  71.),
           ('2013-02-22 13:00:00',  nan, 63,  63.),
           ('2013-02-22 14:00:00',  nan, 60,  60.),
           ('2013-02-22 15:00:00',   5., 62,  62.),
           ('2013-02-22 16:00:00',   8., 62,  62.),
           ('2013-02-25 09:00:00',   4.,  4,  62.),
           ('2013-02-25 10:00:00',   1.,  5,  58.),
           ('2013-02-25 11:00:00',   9., 14,  66.),
           ('2013-02-25 12:00:00',  nan, 14,  64.),
           ('2013-02-25 13:00:00',   5., 19,  64.),
           ('2013-02-25 14:00:00',   4., 23,  62.),
           ('2013-02-25 15:00:00',   5., 28,  66.),
           ('2013-02-25 16:00:00',   3., 31,  61.),
           ('2013-02-26 09:00:00',   9., 40,  65.),
           ('2013-02-26 10:00:00',   9., 49,  72.),
           ('2013-02-26 11:00:00',   4., 53,  71.),
           ('2013-02-26 12:00:00',   6., 59,  72.),
           ('2013-02-26 13:00:00',   9., 68,  81.),
           ('2013-02-26 14:00:00',   3., 71,  84.),
           ('2013-02-26 15:00:00',   1., 72,  80.),
           ('2013-02-26 16:00:00',   2., 74,  74.),
           ('2013-02-27 09:00:00',   4., 74,  74.),
           ('2013-02-27 10:00:00',   5., 78,  78.),
           ('2013-02-27 11:00:00',  nan, 69,  69.),
           ('2013-02-27 12:00:00',   2., 71,  71.),
           ('2013-02-27 13:00:00',   4., 70,  70.),
           ('2013-02-27 14:00:00',   2., 68,  68.),
           ('2013-02-27 15:00:00',   1., 64,  64.),
           ('2013-02-27 16:00:00',   9., 70,  70.),
           ('2013-02-28 09:00:00',   7., 68,  68.),
           ('2013-02-28 10:00:00',   1., 60,  60.),
           ('2013-02-28 11:00:00',   3., 59,  59.),
           ('2013-02-28 12:00:00',   1., 54,  54.),
           ('2013-02-28 13:00:00',   7., 52,  52.),
           ('2013-02-28 14:00:00',   2., 51,  51.),
           ('2013-02-28 15:00:00',   4., 54,  54.),
           ('2013-02-28 16:00:00',   3., 55,  55.),
           ('2013-03-01 09:00:00',   8., 59,  59.),
           ('2013-03-01 10:00:00',   2., 56,  56.),
           ('2013-03-01 11:00:00',   4., 60,  60.),
           ('2013-03-01 12:00:00',   8., 66,  66.),
           ('2013-03-01 13:00:00',   8., 70,  70.),
           ('2013-03-01 14:00:00',   3., 71,  71.),
           ('2013-03-01 15:00:00',   8., 78,  78.),
           ('2013-03-01 16:00:00',   8., 77,  77.),
           ('2013-03-04 09:00:00',   5.,  5,  75.),
           ('2013-03-04 10:00:00',   2.,  7,  76.),
           ('2013-03-04 11:00:00',   1.,  8,  74.),
           ('2013-03-04 12:00:00',   2., 10,  75.),
           ('2013-03-04 13:00:00',   5., 15,  73.),
           ('2013-03-04 14:00:00',   8., 23,  79.),
           ('2013-03-04 15:00:00',   3., 26,  78.),
           ('2013-03-04 16:00:00',   4., 30,  79.),
           ('2013-03-05 09:00:00',   1., 31,  72.),
           ('2013-03-05 10:00:00',   6., 37,  76.),
           ('2013-03-05 11:00:00',   4., 41,  76.),
           ('2013-03-05 12:00:00',   8., 49,  76.),
           ('2013-03-05 13:00:00',   8., 57,  76.),
           ('2013-03-05 14:00:00',   5., 62,  78.),
           ('2013-03-05 15:00:00',   5., 67,  75.),
           ('2013-03-05 16:00:00',   9., 76,  76.),
           ('2013-03-06 09:00:00',   1., 72,  72.),
           ('2013-03-06 10:00:00',  nan, 70,  70.),
           ('2013-03-06 11:00:00',   9., 78,  78.),
           ('2013-03-06 12:00:00',   2., 78,  78.),
           ('2013-03-06 13:00:00',   2., 75,  75.),
           ('2013-03-06 14:00:00',   6., 73,  73.),
           ('2013-03-06 15:00:00',   5., 75,  75.),
           ('2013-03-06 16:00:00',   8., 79,  79.),
           ('2013-03-07 09:00:00',   4., 82,  82.),
           ('2013-03-07 10:00:00',   1., 77,  77.),
           ('2013-03-07 11:00:00',   2., 75,  75.),
           ('2013-03-07 12:00:00',   4., 71,  71.),
           ('2013-03-07 13:00:00',   5., 68,  68.),
           ('2013-03-07 14:00:00',   1., 64,  64.),
           ('2013-03-07 15:00:00',   1., 60,  60.),
           ('2013-03-07 16:00:00',   4., 55,  55.),
           ('2013-03-08 09:00:00',   6., 60,  60.),
           ('2013-03-08 10:00:00',   7., 67,  67.),
           ('2013-03-08 11:00:00',   6., 64,  64.),
           ('2013-03-08 12:00:00',   2., 64,  64.),
           ('2013-03-08 13:00:00',   7., 69,  69.),
           ('2013-03-08 14:00:00',   5., 68,  68.),
           ('2013-03-08 15:00:00',   8., 71,  71.),
           ('2013-03-08 16:00:00',   8., 71,  71.),
           ('2013-03-11 09:00:00',   2.,  2,  69.),
           ('2013-03-11 10:00:00',   3.,  5,  71.),
           ('2013-03-11 11:00:00',   5., 10,  74.),
           ('2013-03-11 12:00:00',   6., 16,  76.),
           ('2013-03-11 13:00:00',  nan, 16,  71.),
           ('2013-03-11 14:00:00',   6., 22,  76.),
           ('2013-03-11 15:00:00',   9., 31,  84.),
           ('2013-03-11 16:00:00',   4., 35,  84.),
           ('2013-03-12 09:00:00',   9., 44,  87.),
           ('2013-03-12 10:00:00',   5., 49,  85.),
           ('2013-03-12 11:00:00',   3., 52,  82.),
           ('2013-03-12 12:00:00',   1., 53,  81.),
           ('2013-03-12 13:00:00',   4., 57,  78.),
           ('2013-03-12 14:00:00',   7., 64,  80.),
           ('2013-03-12 15:00:00',   4., 68,  76.),
           ('2013-03-12 16:00:00',  nan, 68,  68.),
           ('2013-03-13 09:00:00',   5., 71,  71.),
           ('2013-03-13 10:00:00',   3., 71,  71.),
           ('2013-03-13 11:00:00',   9., 75,  75.),
           ('2013-03-13 12:00:00',   1., 70,  70.),
           ('2013-03-13 13:00:00',   6., 76,  76.),
           ('2013-03-13 14:00:00',   8., 78,  78.),
           ('2013-03-13 15:00:00',   3., 72,  72.),
           ('2013-03-13 16:00:00',   5., 73,  73.),
           ('2013-03-14 09:00:00',   7., 71,  71.),
           ('2013-03-14 10:00:00',   7., 73,  73.),
           ('2013-03-14 11:00:00',   7., 77,  77.),
           ('2013-03-14 12:00:00',   8., 84,  84.),
           ('2013-03-14 13:00:00',  nan, 80,  80.),
           ('2013-03-14 14:00:00',   4., 77,  77.),
           ('2013-03-14 15:00:00',   8., 81,  81.),
           ('2013-03-14 16:00:00',   9., 90,  90.),
           ('2013-03-15 09:00:00',   3., 88,  88.),
           ('2013-03-15 10:00:00',   5., 90,  90.),
           ('2013-03-15 11:00:00',   1., 82,  82.),
           ('2013-03-15 12:00:00',   2., 83,  83.),
           ('2013-03-15 13:00:00',   5., 82,  82.),
           ('2013-03-15 14:00:00',   1., 75,  75.),
           ('2013-03-15 15:00:00',   9., 81,  81.),
           ('2013-03-15 16:00:00',   8., 84,  84.),
           ('2013-03-18 09:00:00',   4.,  4,  81.),
           ('2013-03-18 10:00:00',   5.,  9,  79.),
           ('2013-03-18 11:00:00',   7., 16,  79.),
           ('2013-03-18 12:00:00',   4., 20,  75.),
           ('2013-03-18 13:00:00',   2., 22,  77.),
           ('2013-03-18 14:00:00',   1., 23,  74.),
           ('2013-03-18 15:00:00',   8., 31,  74.),
           ('2013-03-18 16:00:00',   2., 33,  67.),
           ('2013-03-19 09:00:00',   8., 41,  72.),
           ('2013-03-19 10:00:00',   4., 45,  71.),
           ('2013-03-19 11:00:00',   9., 54,  79.),
           ('2013-03-19 12:00:00',   2., 56,  79.),
           ('2013-03-19 13:00:00',   1., 57,  75.),
           ('2013-03-19 14:00:00',   5., 62,  79.),
           ('2013-03-19 15:00:00',   5., 67,  75.),
           ('2013-03-19 16:00:00',   8., 75,  75.),
           ('2013-03-20 09:00:00',   6., 77,  77.),
           ('2013-03-20 10:00:00',   7., 79,  79.),
           ('2013-03-20 11:00:00',   9., 81,  81.),
           ('2013-03-20 12:00:00',   8., 85,  85.),
           ('2013-03-20 13:00:00',   4., 87,  87.),
           ('2013-03-20 14:00:00',  nan, 86,  86.),
           ('2013-03-20 15:00:00',   5., 83,  83.),
           ('2013-03-20 16:00:00',   6., 87,  87.),
           ('2013-03-21 09:00:00',   5., 84,  84.),
           ('2013-03-21 10:00:00',   1., 81,  81.),
           ('2013-03-21 11:00:00',   9., 81,  81.),
           ('2013-03-21 12:00:00',   2., 81,  81.),
           ('2013-03-21 13:00:00',   6., 86,  86.),
           ('2013-03-21 14:00:00',   8., 89,  89.),
           ('2013-03-21 15:00:00',   9., 93,  93.),
           ('2013-03-21 16:00:00',   8., 93,  93.),
           ('2013-03-22 09:00:00',   2., 89,  89.),
           ('2013-03-22 10:00:00',   2., 84,  84.),
           ('2013-03-22 11:00:00',   8., 83,  83.),
           ('2013-03-22 12:00:00',   6., 81,  81.),
           ('2013-03-22 13:00:00',   2., 79,  79.),
           ('2013-03-22 14:00:00',  nan, 79,  79.),
           ('2013-03-22 15:00:00',   9., 83,  83.),
           ('2013-03-22 16:00:00',  nan, 77,  77.),
           ('2013-03-25 09:00:00',   6.,  6,  78.),
           ('2013-03-25 10:00:00',   1.,  7,  78.),
           ('2013-03-25 11:00:00',   5., 12,  74.),
           ('2013-03-25 12:00:00',   1., 13,  73.),
           ('2013-03-25 13:00:00',  nan, 13,  67.),
           ('2013-03-25 14:00:00',   2., 15,  61.),
           ('2013-03-25 15:00:00',   9., 24,  61.),
           ('2013-03-25 16:00:00',   7., 31,  60.),
           ('2013-03-26 09:00:00',   3., 34,  61.),
           ('2013-03-26 10:00:00',   7., 41,  66.),
           ('2013-03-26 11:00:00',   2., 43,  60.),
           ('2013-03-26 12:00:00',   5., 48,  59.),
           ('2013-03-26 13:00:00',   4., 52,  61.),
           ('2013-03-26 14:00:00',   3., 55,  64.),
           ('2013-03-26 15:00:00',   1., 56,  56.),
           ('2013-03-26 16:00:00',   4., 60,  60.),
           ('2013-03-27 09:00:00',   8., 62,  62.),
           ('2013-03-27 10:00:00',  nan, 61,  61.),
           ('2013-03-27 11:00:00',   7., 63,  63.),
           ('2013-03-27 12:00:00',   1., 63,  63.),
           ('2013-03-27 13:00:00',   8., 71,  71.),
           ('2013-03-27 14:00:00',   8., 77,  77.),
           ('2013-03-27 15:00:00',   4., 72,  72.),
           ('2013-03-27 16:00:00',   2., 67,  67.),
           ('2013-03-28 09:00:00',   3., 67,  67.),
           ('2013-03-28 10:00:00',   9., 69,  69.),
           ('2013-03-28 11:00:00',   3., 70,  70.),
           ('2013-03-28 12:00:00',   7., 72,  72.),
           ('2013-03-28 13:00:00',   3., 71,  71.),
           ('2013-03-28 14:00:00',   7., 75,  75.),
           ('2013-03-28 15:00:00',   6., 80,  80.),
           ('2013-03-28 16:00:00',   4., 80,  80.),
           ('2013-03-29 09:00:00',   1., 73,  73.),
           ('2013-03-29 10:00:00',   3., 76,  76.),
           ('2013-03-29 11:00:00',   6., 75,  75.),
           ('2013-03-29 12:00:00',   5., 79,  79.),
           ('2013-03-29 13:00:00',  nan, 71,  71.),
           ('2013-03-29 14:00:00',   6., 69,  69.),
           ('2013-03-29 15:00:00',   3., 68,  68.),
           ('2013-03-29 16:00:00',   8., 74,  74.),
           ('2013-04-01 09:00:00',   6.,  6,  77.),
           ('2013-04-01 10:00:00',   1.,  7,  69.),
           ('2013-04-01 11:00:00',   7., 14,  73.),
           ('2013-04-01 12:00:00',   3., 17,  69.),
           ('2013-04-01 13:00:00',   4., 21,  70.),
           ('2013-04-01 14:00:00',   5., 26,  68.),
           ('2013-04-01 15:00:00',   8., 34,  70.),
           ('2013-04-01 16:00:00',   2., 36,  68.)], 
          dtype=[('datetime', 'O'), ('trips', '<f8'), ('sum()', '<i8'), ('expected', '<f8')])

```

</details>


#### Problem description

When performing rolling operations on a timestamp index by a daily timedelta the values are not rolling and regurarly "reset".

#### Expected Output

The array (with expected values) has been provided above.

#### Output of ``pd.show_versions()``


<details>

INSTALLED VERSIONS
------------------
commit: None
python: 3.6.1.final.0
python-bits: 64
OS: Linux
OS-release: 4.4.0-89-generic
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: None
LANG: en_US.UTF-8
LOCALE: en_US.UTF-8

pandas: 0.20.3
pytest: 3.0.7
pip: 9.0.1
setuptools: 36.2.7
Cython: 0.25.2
numpy: 1.13.1
scipy: 0.19.0
xarray: None
IPython: 5.3.0
sphinx: 1.5.6
patsy: 0.4.1
dateutil: 2.6.1
pytz: 2017.2
blosc: None
bottleneck: 1.2.1
tables: 3.3.0
numexpr: 2.6.2
feather: None
matplotlib: 2.0.2
openpyxl: 2.4.7
xlrd: 1.0.0
xlwt: 1.2.0
xlsxwriter: 0.9.6
lxml: 3.7.3
bs4: 4.6.0
html5lib: 0.999
sqlalchemy: 1.1.9
pymysql: None
psycopg2: 2.7.3 (dt dec pq3 ext lo64)
jinja2: 2.9.6
s3fs: None
pandas_gbq: None
pandas_datareader: None

</details>
