ImportError on RangeIndex
- In system env, I am not able to import pandas after updating to 0.18.0.  Installed/updated by conda on Win 8.1.  
- running
  1. `conda remove pandas`
  2. `conda install pandas`
  
  does not help
- after installing into fresh new virtual env, import works.

Probably it is bad state of the environment, could you please advise me how to fix it?
#### ImportError on importing

``` bash
C:\WINDOWS\system32>python
Python 2.7.11 |Anaconda 2.3.0 (64-bit)| (default, Feb 16 2016, 09:58:36) [MSC v.
1500 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
Anaconda is brought to you by Continuum Analytics.
Please check out: http://continuum.io/thanks and https://anaconda.org
>>> import pandas
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Program Files\Anaconda\lib\site-packages\pandas\__init__.py", line 44
, in <module>
    from pandas.core.api import *
  File "C:\Program Files\Anaconda\lib\site-packages\pandas\core\api.py", line 10
, in <module>
    from pandas.core.groupby import Grouper
  File "C:\Program Files\Anaconda\lib\site-packages\pandas\core\groupby.py", lin
e 18, in <module>
    from pandas.core.frame import DataFrame
  File "C:\Program Files\Anaconda\lib\site-packages\pandas\core\frame.py", line
5230, in <module>
    _EMPTY_SERIES = Series([])
  File "C:\Program Files\Anaconda\lib\site-packages\pandas\core\series.py", line
 216, in __init__
    index = _default_index(len(data))
  File "C:\Program Files\Anaconda\lib\site-packages\pandas\core\common.py", line
 1867, in _default_index
    from pandas.core.index import RangeIndex
ImportError: cannot import name RangeIndex
```
#### conda information

C:\WINDOWS\system32>conda list pandas
# packages in environment at C:\Program Files\Anaconda:
#
pandas                    0.18.0              np110py27_0
#### output of `pd.show_versions()`

Not available.
