Indexing with hierarchical index issue
I'm using pandas 0.12.0 and having issue with accessing hierarchically indexed data frame elements using the ix. As a note, the issue is coming only when I have datetime objects in level 0 of hierarchical index. 

arrays = [date_range('2013-11-15', periods=4).repeat(2),
             ['one', 'two', 'one', 'two', 'one', 'two', 'one', 'two']]
tuples = list(zip(*arrays))
index = MultiIndex.from_tuples(tuples, names=['first', 'second'])
df = DataFrame(randn(8, 3), index=index, columns=['A', 'B', 'C'])
df.ix['2013-11-15', 'one']

---

KeyError                                  Traceback (most recent call last)
<ipython-input-99-c55bdd03164b> in <module>()
----> 1 df.ix['2013-11-15', 'one']

~/env/lib/python2.6/site-packages/pandas/core/indexing.pyc in **getitem**(self, key)
     45                 pass
     46 
---> 47             return self._getitem_tuple(key)
     48         else:
     49             return self._getitem_axis(key, axis=0)

~/env/lib/python2.6/site-packages/pandas/core/indexing.pyc in _getitem_tuple(self, tup)
    251     def _getitem_tuple(self, tup):
    252         try:
--> 253             return self._getitem_lowerdim(tup)
    254         except IndexingError:
    255             pass

~/env/lib/python2.6/site-packages/pandas/core/indexing.pyc in _getitem_lowerdim(self, tup)
    384                         new_key, = new_key
    385 
--> 386                 return getattr(section,self.name)[new_key]
    387 
    388         raise IndexingError('not applicable')

~/env/lib/python2.6/site-packages/pandas/core/indexing.pyc in **getitem**(self, key)
     45                 pass
     46 
---> 47             return self._getitem_tuple(key)
     48         else:
     49             return self._getitem_axis(key, axis=0)

~/env/lib/python2.6/site-packages/pandas/core/indexing.pyc in _getitem_tuple(self, tup)
    251     def _getitem_tuple(self, tup):
    252         try:
--> 253             return self._getitem_lowerdim(tup)
    254         except IndexingError:
    255             pass

~/env/lib/python2.6/site-packages/pandas/core/indexing.pyc in _getitem_lowerdim(self, tup)
    361         for i, key in enumerate(tup):
    362             if _is_label_like(key) or isinstance(key, tuple):
--> 363                 section = self._getitem_axis(key, axis=i)
    364 
    365                 # we have yielded a scalar ?

~/env/lib/python2.6/site-packages/pandas/core/indexing.pyc in _getitem_axis(self, key, axis)
    411                     return self._get_loc(key, axis=axis)
    412 
--> 413             return self._get_label(key, axis=axis)
    414 
    415     def _getitem_iterable(self, key, axis=0):

~/env/lib/python2.6/site-packages/pandas/core/indexing.pyc in _get_label(self, label, axis)
     59             return self.obj._xs(label, axis=axis, copy=False)
     60         except Exception:
---> 61             return self.obj._xs(label, axis=axis, copy=True)
     62 
     63     def _get_loc(self, key, axis=0):

~/env/lib/python2.6/site-packages/pandas/core/frame.pyc in xs(self, key, axis, level, copy)
   2358 
   2359         if axis == 1:
-> 2360             data = self[key]
   2361             if copy:
   2362                 data = data.copy()

/u/pullurur/dig/quantinvest/env/lib/python2.6/site-packages/pandas/core/frame.pyc in **getitem**(self, key)
   2001             # get column
   2002             if self.columns.is_unique:
-> 2003                 return self._get_item_cache(key)
   2004 
   2005             # duplicate columns

~/env/lib/python2.6/site-packages/pandas/core/generic.pyc in _get_item_cache(self, item)
    665             return cache[item]
    666         except Exception:
--> 667             values = self._data.get(item)
    668             res = self._box_item_values(item, values)
    669             cache[item] = res

~/env/lib/python2.6/site-packages/pandas/core/internals.pyc in get(self, item)
   1653     def get(self, item):
   1654         if self.items.is_unique:
-> 1655             _, block = self._find_block(item)
   1656             return block.get(item)
   1657         else:

~/env/lib/python2.6/site-packages/pandas/core/internals.pyc in _find_block(self, item)
   1933 
   1934     def _find_block(self, item):
-> 1935         self._check_have(item)
   1936         for i, block in enumerate(self.blocks):
   1937             if item in block:

~/env/lib/python2.6/site-packages/pandas/core/internals.pyc in _check_have(self, item)
   1940     def _check_have(self, item):
   1941         if item not in self.items:
-> 1942             raise KeyError('no item named %s' % com.pprint_thing(item))
   1943 
   1944     def reindex_axis(self, new_axis, method=None, axis=0, copy=True):

KeyError: u'no item named one'
