DeprecationWarning in __init__.py:7: bad escape \s
When setting the warnings filter to show DeprecationWarnings, I get a warning when importing Pandas (which I discovered because mne-python changes the global warning settings, see https://github.com/mne-tools/mne-python/issues/2870):

```
import warnings
warnings.simplefilter("default")
import pandas as pd
```

This results in the following warning message:

```
/usr/local/lib/python3.5/site-packages/pandas/__init__.py:7: DeprecationWarning: bad escape \s
from pandas import hashtable, tslib, lib
```

I have no idea what's wrong with the code in line 7 though. Here's the output of `pd.show_versions()`:

```
INSTALLED VERSIONS
------------------
commit: None
python: 3.5.1.final.0
python-bits: 64
OS: Darwin
OS-release: 15.3.0
machine: x86_64
processor: i386
byteorder: little
LC_ALL: en_US.UTF-8
LANG: en_US.UTF-8

pandas: 0.17.1
nose: 1.3.7
pip: 8.0.2
setuptools: 20.1
Cython: 0.23.4
numpy: 1.10.4
scipy: 0.17.0
statsmodels: None
IPython: 4.1.1
sphinx: 1.3.5
patsy: 0.4.1
dateutil: 2.4.2
pytz: 2015.7
blosc: None
bottleneck: None
tables: None
numexpr: None
matplotlib: 1.5.1
openpyxl: None
xlrd: None
xlwt: None
xlsxwriter: None
lxml: None
bs4: None
html5lib: None
httplib2: None
apiclient: None
sqlalchemy: None
pymysql: None
psycopg2: None
Jinja2: 2.8
```
