MagicMock a pandas DataFrame causes a segfault
#### Code Sample

```python
import pandas as pd
from mock import MagicMock

df = pd.DataFrame(0, [[1, 2], [3, 4]], ['col'])
df['col'] += MagicMock()
```
#### Problem description

I have a function that returns a column of dataframe. I want to mock out this function and test it is called with the correct args. The above code segs outs in 0.24.1 but not in 0.23.4.

#### Expected Output
Not to seg fault

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

<details>

INSTALLED VERSIONS
------------------

commit: None
python: 2.7.12.final.0
python-bits: 64
OS: Linux
OS-release: 4.4.0-142-generic
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: None
LANG: en_US
LOCALE: None.None

pandas: 0.24.1
pytest: None
pip: 19.0.2
setuptools: 40.8.0
Cython: None
numpy: 1.16.1
scipy: 1.2.1
pyarrow: None
xarray: None
IPython: None
sphinx: None
patsy: None
dateutil: 2.8.0
pytz: 2018.9
blosc: None
bottleneck: None
tables: None
numexpr: None
feather: None
matplotlib: None
openpyxl: None
xlrd: None
xlwt: None
xlsxwriter: None
lxml.etree: None
bs4: None
html5lib: None
sqlalchemy: 1.2.17
pymysql: None
psycopg2: 2.7.7 (dt dec pq3 ext lo64)
jinja2: None
s3fs: None
fastparquet: None
pandas_gbq: None
pandas_datareader: None
gcsfs: None
</details>
