R1:3b6100d620ef

Fix lookup of commits in Subversion

Summary:
Fixes T7122. The way this query works is a little surprising:

- If executed as `withRepositoryIDs(...)`, it assumes you are passing one //or more// repository IDs, so it will never resolve ambiguous identifiers (e.g., "123" instead of "rSVN123").
- If executed as `withRepository(...)`, it knows you are passing exactly one repository and will use that to imply context and resolve these identifiers correctly.

This isn't very obvious from the API, but I'm…