shallow: add repository argument to is_repository_shallow

Add a repository argument to allow callers of is_repository_shallow
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/pack-objects.c b/builtin/pack-objects.c
index 97a5963..0f1eec2 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -2857,7 +2857,7 @@ static void get_object_list(int ac, const char **av)
 	setup_revisions(ac, av, &revs, NULL);
 
 	/* make sure shallows are read */
-	is_repository_shallow();
+	is_repository_shallow(the_repository);
 
 	while (fgets(line, sizeof(line), stdin) != NULL) {
 		int len = strlen(line);
@@ -3142,7 +3142,7 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 		use_bitmap_index = use_bitmap_index_default;
 
 	/* "hard" reasons not to use bitmaps; these just won't work at all */
-	if (!use_internal_rev_list || (!pack_to_stdout && write_bitmap_index) || is_repository_shallow())
+	if (!use_internal_rev_list || (!pack_to_stdout && write_bitmap_index) || is_repository_shallow(the_repository))
 		use_bitmap_index = 0;
 
 	if (pack_to_stdout || !rev_list_all)