R1:ed508247ba1a

Fix a bug in the SVN parser which causes it to find commit refs in other SVN
repositories

Summary:
This query isn't scoped correctly to the repository ID, so we may identify
commits from other repositories.

This causes a somewhat subtle issue since we only use it to manage file
copies/moves, so you end up with a file "copied from" the same revision in
another repository. I think the UI probably even renders correctly.

Once I finish T325 and better understand what's going on here, I'll see how much
work…