- Missing / empty data fields other than branch_id no longer affect
changeset aggregation
- Needed for VSS, which lacks time information on deletes
- If all revs have change_ids, they are now sorted by change_id
and name (as opposed to change_id, rev_id)
- VCP::Rev::sort_time() removed
- VCP::Filter::changesets has better debugging
- TestUtils now dumps large diffs