regression in 0.24: np.clip does not work for some values of a_min
#### Code Sample

```python
import pandas as pd
import numpy as np
print(pd.__name__,pd.__version__,np.__name__,np.__version__)
np.clip(pd.Series([0,1,0,1]), 1e-7, 1)
np.clip(pd.Series([0,1,0,1]), 1e-8, 1)
np.clip(pd.Series([0.0,1.0,0.0,1.0]), 1e-8, 1)
```

#### Problem description

With pandas `0.23.4`, [`numpy.clip`](https://docs.scipy.org/doc/numpy-1.15.1/reference/generated/numpy.clip.html) works as expected, producing a `Series` of type `float64` for any `min` argument.

With pandas `0.24.0`, it works up to 1e-7 but not for 1e-8
```python
>>> np.clip(pd.Series([0,1,0,1]), 1e-7, 1)
0    1.000000e-07
1    1.000000e+00
2    1.000000e-07
3    1.000000e+00
dtype: float64
>>> np.clip(pd.Series([0,1,0,1]), 1e-8, 1)
0    0
1    1
2    0
3    1
dtype: int64
```

This is an unwelcome change from the previous version.

#### Expected Output

```python
>>> np.clip(pd.Series([0,1,0,1]), 1e-7, 1)
0    1.000000e-07
1    1.000000e+00
2    1.000000e-07
3    1.000000e+00
dtype: float64
>>> np.clip(pd.Series([0,1,0,1]), 1e-8, 1)
0    1.000000e-08
1    1.000000e+00
2    1.000000e-08
3    1.000000e+00
dtype: float64
>>> np.clip(pd.Series([0,1,0,1]), 1e-15, 1)
0    1.000000e-15
1    1.000000e+00
2    1.000000e-15
3    1.000000e+00
dtype: float64
```

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

<details>
INSTALLED VERSIONS
------------------
commit: None
python: 3.7.2.final.0
python-bits: 64
OS: Darwin
OS-release: 17.7.0
machine: x86_64
processor: i386
byteorder: little
LC_ALL: en_US.UTF-8
LANG: C
LOCALE: en_US.UTF-8

pandas: 0.24.0
pytest: None
pip: 19.0.1
setuptools: 40.7.0
Cython: None
numpy: 1.16.0
scipy: 1.2.0
pyarrow: None
xarray: None
IPython: 7.2.0
sphinx: None
patsy: None
dateutil: 2.7.5
pytz: 2018.9
blosc: None
bottleneck: None
tables: None
numexpr: None
feather: None
matplotlib: 3.0.2
openpyxl: None
xlrd: 1.2.0
xlwt: None
xlsxwriter: 1.1.2
lxml.etree: 4.3.0
bs4: None
html5lib: None
sqlalchemy: 1.2.17
pymysql: None
psycopg2: 2.7.7 (dt dec pq3 ext lo64)
jinja2: 2.10
s3fs: None
fastparquet: None
pandas_gbq: None
pandas_datareader: None
gcsfs: None
</details>
