Error with feedstocks

Log from conda-forge-maint is shown below. Seems that an undefined attribute is being accessed.

```
2016-09-28T02:05:16.467061+00:00 app[scheduler.6009]: urllib3-feedstock was checked, and is up-to-date
2016-09-28T02:05:16.570490+00:00 app[scheduler.6009]: Traceback (most recent call last):
2016-09-28T02:05:16.570492+00:00 app[scheduler.6009]: File "/tmp/conda-execute_d9wt08u7", line 230, in
2016-09-28T02:05:16.570493+00:00 app[scheduler.6009]: for feedstock, git_ref, meta_content, recipe in feedstock_gen:
2016-09-28T02:05:16.570494+00:00 app[scheduler.6009]: File "/app/.conda/tmp_envs/e51aaf2a2e07c87d7cc9/lib/python3.5/site-packages/conda_smithy/feedstocks.py", line 230, in feedstocks_yaml
2016-09-28T02:05:16.570495+00:00 app[scheduler.6009]: for repo, feedstock in feedstocks_repos(organization, feedstocks_directory, **feedstocks_repo_kwargs):
2016-09-28T02:05:16.570496+00:00 app[scheduler.6009]: upstream = repo.remotes.upstream
2016-09-28T02:05:16.570496+00:00 app[scheduler.6009]: File "/app/.conda/tmp_envs/e51aaf2a2e07c87d7cc9/lib/python3.5/site-packages/conda_smithy/feedstocks.py", line 173, in feedstocks_repos
2016-09-28T02:05:16.570497+00:00 app[scheduler.6009]: File "/app/.conda/tmp_envs/e51aaf2a2e07c87d7cc9/lib/python3.5/site-packages/git/util.py", line 697, in __getattr__
2016-09-28T02:05:16.570498+00:00 app[scheduler.6009]: return list.__getattribute__(self, attr)
2016-09-28T02:05:16.570498+00:00 app[scheduler.6009]: AttributeError: 'IterableList' object has no attribute 'upstream'
2016-09-28T02:05:17.803759+00:00 app[scheduler.6009]: CalledProcessError: Command '['python', '/tmp/conda-execute_d9wt08u7', '--feedstocks-dir', 'feedstocks', '--limit', '20']' returned non-zero exit status 1
2016-09-28T02:05:19.078542+00:00 heroku[scheduler.6009]: Process exited with status 1
2016-09-28T02:05:19.088649+00:00 heroku[scheduler.6009]: State changed from up to complete
```