Merge branch 'ds/backfill-revs'

`git backfill` learned to accept revision and pathspec arguments.

* ds/backfill-revs:
  t5620: test backfill's unknown argument handling
  path-walk: support wildcard pathspecs for blob filtering
  backfill: work with prefix pathspecs
  backfill: accept revision arguments
  t5620: prepare branched repo for revision tests
  revision: include object-name.h