Merge branch 'jk/repack-no-explode-objects-from-old-pack' into maint

"git repack" used to write out unreachable objects as loose objects when repacking, even if such loose objects will immediately pruned due to its age. By Jeff King * jk/repack-no-explode-objects-from-old-pack: gc: use argv-array for sub-commands argv-array: add a new "pushl" method argv-array: refactor empty_argv initialization gc: do not explode objects which will be immediately pruned