pandas concat working in 0.12 but not 0.13
I have a long list of dataframes that concat fine in 0.12 but not in 0.13.  Has anyone seen this error?
I am concatenating using the following

```
pd.concat(all_gics, ignore_index=True) 
```

My traceback:

/usr/anaconda/lib/python2.7/site-packages/pandas/tools/merge.pyc in concat(objs, axis, join, join_axes, ignore_index, keys, levels, names, verify_integrity)
    925                        keys=keys, levels=levels, names=names,
    926                        verify_integrity=verify_integrity)
--> 927     return op.get_result()
    928 
    929 

/usr/anaconda/lib/python2.7/site-packages/pandas/tools/merge.pyc in get_result(self)
   1016             return tmpdf
   1017         else:
-> 1018             new_data = self._get_concatenated_data()
   1019             new_data = self._post_merge(new_data)
   1020             return self.objs[0]._from_axes(new_data, self.new_axes)

/usr/anaconda/lib/python2.7/site-packages/pandas/tools/merge.pyc in _get_concatenated_data(self)
   1075             new_data = {}
   1076             for item in self.new_axes[0]:
-> 1077                 new_data[item] = self._concat_single_item(rdata, item)
   1078 
   1079         return new_data

/usr/anaconda/lib/python2.7/site-packages/pandas/tools/merge.pyc in _concat_single_item(self, objs, item)
   1184                     elif isnull(v).all():
   1185 
-> 1186                         alls.remove('other')
   1187                         alls.remove('object')
   1188 

KeyError: 'other'
