MultiIndex.from_tuples issue
from mailing list cc @ruidc 

```
import pandas
mix = pandas.MultiIndex.from_tuples([('1a', '2a'), ('1a', '2b'), ('1a', '2c'), ('1b', '2d')])
df = pandas.DataFrame([[1,2,3,4],[5,6,7,8]], columns=mix)
#... manipulate columns here ... but not required to raise error here
df.columns = pandas.MultiIndex.from_tuples(df.columns) #df.columns.values works fine

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Python27\lib\site-packages\pandas\core\index.py", line 1538, in from_tuples
    arrays = list(lib.tuples_to_object_array(tuples).T)
  File "inference.pyx", line 687, in pandas.lib.tuples_to_object_array (pandas\src\tseries.c:97580)
IndexError: Out of bounds on buffer access (axis 0)

Is this a miss-use of from_tuples?
```

```
import pandas
mix = pandas.MultiIndex.from_tuples([('1a', '2a'), ('1a', '2b'), ('1a', '2c')])
df = pandas.DataFrame([[1,2],[3,4],[5,6]], index=mix)
s = pandas.Series({(1,1): 1, (1,2): 2})
#df['new'] = s.to_dict() # Nice AssertionError about length mismatch
df['new'] = s #bad kaboom on rc2, loads NaNs on b2 as expected


Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Python27\lib\site-packages\pandas\core\frame.py", line 1712, in __setitem__
    self._set_item(key, value)
  File "C:\Python27\lib\site-packages\pandas\core\frame.py", line 1751, in _set_item
    value = self._sanitize_column(key, value)
  File "C:\Python27\lib\site-packages\pandas\core\frame.py", line 1778, in _sanitize_column
    value = value.reindex(self.index).values
  File "C:\Python27\lib\site-packages\pandas\core\series.py", line 2044, in reindex
    level=level, limit=limit)
  File "C:\Python27\lib\site-packages\pandas\core\index.py", line 791, in reindex
    limit=limit)
  File "C:\Python27\lib\site-packages\pandas\core\index.py", line 722, in get_indexer
    indexer = self._engine.get_indexer(target)
  File "engines.pyx", line 245, in pandas.lib.IndexEngine.get_indexer (pandas\src\tseries.c:105931)
  File "hashtable.pyx", line 751, in pandas.lib.PyObjectHashTable.lookup (pandas\src\tseries.c:21174)
```
