Merge branch 'jk/ignore-broken-tags-when-ignoring-missing-links' into maint

Tag objects, which are not reachable from any ref, that point at
missing objects were mishandled by "git gc" and friends (they
should silently be ignored instead)

* jk/ignore-broken-tags-when-ignoring-missing-links:
  revision.c: ignore broken tags with ignore_missing_links

revision.c

@@ -230,7 +230,7 @@ static struct commit *handle_commit(struct rev_info *revs,
 			die("bad tag");
 		object = parse_object(tag->tagged->oid.hash);
 		if (!object) {
-			if (flags & UNINTERESTING)
+			if (revs->ignore_missing_links || (flags & UNINTERESTING))
 				return NULL;
 			die("bad object %s", oid_to_hex(&tag->tagged->oid));
 		}

t/t6501-freshen-objects.sh

@@ -129,7 +129,7 @@ for repack in '' true; do
 	'
 done
 
-test_expect_success 'do not complain about existing broken links' '
+test_expect_success 'do not complain about existing broken links (commit)' '
 	cat >broken-commit <<-\EOF &&
 	tree 0000000000000000000000000000000000000001
 	parent 0000000000000000000000000000000000000002
@@ -144,4 +144,29 @@ test_expect_success 'do not complain about existing broken links' '
 	test_must_be_empty stderr
 '
 
+test_expect_success 'do not complain about existing broken links (tree)' '
+	cat >broken-tree <<-\EOF &&
+	100644 blob 0000000000000000000000000000000000000003	foo
+	EOF
+	tree=$(git mktree --missing <broken-tree) &&
+	git gc 2>stderr &&
+	git cat-file -e $tree &&
+	test_must_be_empty stderr
+'
+
+test_expect_success 'do not complain about existing broken links (tag)' '
+	cat >broken-tag <<-\EOF &&
+	object 0000000000000000000000000000000000000004
+	type commit
+	tag broken
+	tagger whatever <whatever@example.com> 1234 -0000
+
+	this is a broken tag
+	EOF
+	tag=$(git hash-object -t tag -w broken-tag) &&
+	git gc 2>stderr &&
+	git cat-file -e $tag &&
+	test_must_be_empty stderr
+'
+
 test_done