commit: add repository argument to lookup_commit_reference

Add a repository argument to allow callers of lookup_commit_reference
to be more specific about which repository to handle. This is a small
mechanical change; it doesn't change the implementation to handle
repositories other than the_repository yet.

As with the previous commits, use a macro to catch callers passing a
repository other than the_repository at compile time.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin/replace.c b/builtin/replace.c
index deabda2..0232f98 100644
--- a/builtin/replace.c
+++ b/builtin/replace.c
@@ -371,7 +371,7 @@ static int replace_parents(struct strbuf *buf, int argc, const char **argv)
 			return error(_("Not a valid object name: '%s'"),
 				     argv[i]);
 		}
-		if (!lookup_commit_reference(&oid)) {
+		if (!lookup_commit_reference(the_repository, &oid)) {
 			strbuf_release(&new_parents);
 			return error(_("could not parse %s"), argv[i]);
 		}
@@ -443,7 +443,7 @@ static int create_graft(int argc, const char **argv, int force, int gentle)
 
 	if (get_oid(old_ref, &old_oid) < 0)
 		return error(_("Not a valid object name: '%s'"), old_ref);
-	commit = lookup_commit_reference(&old_oid);
+	commit = lookup_commit_reference(the_repository, &old_oid);
 	if (!commit)
 		return error(_("could not parse %s"), old_ref);