R1:f68d67530aef

Fix an issue with pulling Subversion blame data

Summary:
Fixes T4067. The way `DiffusionCommitQuery` works prevents it from loading SVN identifiers in some cases without additional constraints, since "12345" might be an SVN revision 12345, or it might be the first 5 characters of a Git commit hash.

Introduce `withRepository()` as a shorthand for `withDefaultRepository()` + `withRepositoryIDs()`. This tells the query to:

- Only look in the given repository; and
- use the more liberal identifier…