Only use remote branches for our syncing.
Only use remote branches for our syncing.

We don't care about branches local to us.
This causes bugs where a local and remote branch have the same name,
and we sync `stable` in and endless loop.

Fixes #4980

rtfd/readthedocs.org,rtfd/readthedocs.org,rtfd/readthedocs.org,rtfd/readthedocs.org