DataFrame.resample has a bug that produces NaN with some specific indices.
might be related to #3849

This bug can be reproduced with 0.11.1.dev-0538c43 and 0.11.0.

The following code should keep the values on 2012-09-12, 2012-09-19, and 2012-09-26 and insert NaN between these dates. However, the values of all rows between 2012-09-12 to 2012-09-26 are NaN.

``` python
import pandas as pd
pd.DataFrame({'value':[1,2,3]},index= pd.Series([pd.Timestamp('2012-09-12 10:00:00'),  pd.Timestamp('2012-09-19 10:00:00'), pd.Timestamp('2012-09-26 10:00:00')])).resample('D')
```

Output:

```
            value
2012-09-12    NaN
2012-09-13    NaN
2012-09-14    NaN
2012-09-15    NaN
2012-09-16    NaN 
2012-09-17    NaN
2012-09-18    NaN
2012-09-19    NaN
2012-09-20    NaN
2012-09-21    NaN
2012-09-22    NaN
2012-09-23    NaN
2012-09-24    NaN
2012-09-25    NaN 
2012-09-26    NaN
```

The weird thing was, if I changed the time of one index slightly, the output became correct.

``` python
pd.DataFrame({'value':[1,2,3]},index= pd.Series([pd.Timestamp('2012-09-12 10:00:00'),  pd.Timestamp('2012-09-19 10:00:00'), pd.Timestamp('2012-09-26 00:00:00')])).resample('D')
```

```
            value
2012-09-12      1
2012-09-13    NaN
2012-09-14    NaN
2012-09-15    NaN
2012-09-16    NaN
2012-09-17    NaN
2012-09-18    NaN
2012-09-19      2
2012-09-20    NaN
2012-09-21    NaN
2012-09-22    NaN
2012-09-23    NaN
2012-09-24    NaN
2012-09-25    NaN
2012-09-26      3
```
