Can't index into anndata object with integer obs_names

Trying to index into an AnnData object which has integer obs_names throws an assertion error. I expected either not allowing the construction an object with integer obs_names or allowing indexing into them.

Here’s a quick example. First I instantiate an AnnData object, give it integers for observation names, then get an error when I try to index into it:

>>> import scanpy.api as sc
>>> import pandas as pd
>>> import numpy as np
>>> adata = sc.datasets.krumsiek11()
Observation names are not unique. To make them unique, call `.obs_names_make_unique`.
... storing 'cell_type' as categorical
>>> adata.obs_names = np.array(range(adata.n_obs))
>>> adata[:, ['Gata2', 'Gata1']]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.6/site-packages/anndata/base.py", line 1211, in __getitem__
    return self._getitem_view(index)
  File "/usr/local/lib/python3.6/site-packages/anndata/base.py", line 1214, in _getitem_view
    oidx, vidx = self._normalize_indices(index)
  File "/usr/local/lib/python3.6/site-packages/anndata/base.py", line 1190, in _normalize_indices
    obs = _normalize_index(obs, self.obs_names)
  File "/usr/local/lib/python3.6/site-packages/anndata/base.py", line 231, in _normalize_index
    'Don’t call _normalize_index with non-categorical/string names'
AssertionError: Don’t call _normalize_index with non-categorical/string names

This error in indexing can be recovered by using a pandas.RangeIndex for the observation names:

>>> adata.obs_names = pd.RangeIndex(stop=adata.n_obs)
>>> adata[:, ['Gata2', 'Gata1']]
View of AnnData object with n_obs × n_vars = 640 × 2 
    obs: 'cell_type'
    uns: 'iroot', 'highlights'

However, range indexes are frequently implicitly replaced with integer indexes:

>>> adata_norm = sc.pp.normalize_per_cell(adata, copy=True)
>>> adata_norm.obs_names
Int64Index([  0,   1,   2,   3,   4,   5,   6,   7,   8,   9,
            ...
            630, 631, 632, 633, 634, 635, 636, 637, 638, 639],
           dtype='int64', length=640)
>>> adata_norm[:, ['Gata2', 'Gata1']]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.6/site-packages/anndata/base.py", line 1211, in __getitem__
    return self._getitem_view(index)
  File "/usr/local/lib/python3.6/site-packages/anndata/base.py", line 1214, in _getitem_view
    oidx, vidx = self._normalize_indices(index)
  File "/usr/local/lib/python3.6/site-packages/anndata/base.py", line 1190, in _normalize_indices
    obs = _normalize_index(obs, self.obs_names)
  File "/usr/local/lib/python3.6/site-packages/anndata/base.py", line 231, in _normalize_index
    'Don’t call _normalize_index with non-categorical/string names'
AssertionError: Don’t call _normalize_index with non-categorical/string names

Thanks!