Merge branch 'jt/no-abuse-alternate-odb-for-submodules'

Follow through the work to use the repo interface to access
submodule objects in-process, instead of abusing the alternate
object database interface.

* jt/no-abuse-alternate-odb-for-submodules:
  submodule: trace adding submodule ODB as alternate
  submodule: pass repo to check_has_commit()
  object-file: only register submodule ODB if needed
  merge-{ort,recursive}: remove add_submodule_odb()
  refs: peeling non-the_repository iterators is BUG
  refs: teach arbitrary repo support to iterators
  refs: plumb repo into ref stores

diff --cc merge-ort.c
Simple merge

diff --cc merge-recursive.c
Simple merge

diff --cc object-file.c
Simple merge

diff --cc refs.c
Simple merge

diff --cc refs/files-backend.c
Simple merge

diff --cc refs/packed-backend.c
Simple merge

diff --cc refs/ref-cache.c
Simple merge

diff --cc refs/ref-cache.h
Simple merge

diff --cc refs/refs-internal.h
Simple merge

diff --cc strbuf.h
Simple merge

diff --cc submodule.c
Simple merge

diff --cc t/README
Simple merge