Merge branch 'ac/prune-wo-the-repository'

Some code paths in the "git prune" used to ignore passed in
repository object and used the_repository singleton instance
instead, which has been corrected.

* ac/prune-wo-the-repository:
  builtin/prune: stop depending on 'the_repository'
  repository: move 'repository_format_precious_objects' to repo scope

diff --cc builtin/gc.c
Simple merge