Merge branch 'sb/object-store-replace'

Hotfix.

* sb/object-store-replace:
  get_main_ref_store: BUG() when outside a repository
  object.c: clear replace map before freeing it
  replace-object.c: remove the_repository from prepare_replace_object
  object.c: free replace map in raw_object_store_clear

refs.c

@@ -1668,6 +1668,9 @@ struct ref_store *get_main_ref_store(struct repository *r)
 	if (r->refs)
 		return r->refs;
 
+	if (!r->gitdir)
+		BUG("attempting to get main_ref_store outside of repository");
+
 	r->refs = ref_store_init(r->gitdir, REF_STORE_ALL_CAPS);
 	return r->refs;
 }