invalid dtype access crashes interpreter (segfault)
In [1]: from pandas import *

In [2]: df = DataFrame([1,2,3,4], index=['a','b','c','d'])

In [3]: df
Out[3]: 
   0
a  1
b  2
c  3
d  4

In [4]: df.dtypes
Out[4]: 0    int64

In [5]: df.dtypes[0]
Out[5]: dtype('int64')

In [6]: df.dtypes[1]
**\* glibc detected **\* /home/adam/.virtualenvs/py27/bin/python: free(): corrupted unsorted chunks: 0x00000000025db8e0 ***
======= Backtrace: =========
/lib/x86_64-linux-gnu/libc.so.6(+0x78a96)[0x7f8751957a96]
/lib/x86_64-linux-gnu/libc.so.6(cfree+0x6c)[0x7f875195bd7c]
/home/adam/.virtualenvs/py27/bin/python[0x4354d8]
/home/adam/.virtualenvs/py27/bin/python[0x447a2c]
/home/adam/.virtualenvs/py27/bin/python[0x4e4fe3]
/home/adam/.virtualenvs/py27/bin/python[0x4e500d]
======= Memory map: ========
00400000-00633000 r-xp 00000000 08:05 5373988                            /home/adam/.virtualenvs/py27/bin/python
00832000-00833000 r--p 00232000 08:05 5373988                            /home/adam/.virtualenvs/py27/bin/python
00833000-0089c000 rw-p 00233000 08:05 5373988                            /home/adam/.virtualenvs/py27/bin/python
0089c000-008ae000 rw-p 00000000 00:00 0 
016f0000-0278e000 rw-p 00000000 00:00 0                                  [heap]
