git branch -m: forbid renaming of a symref

There may be cases where one would really want to rename the symbolic
ref without changing its value, but "git branch -m" is not such a
use-case.

Signed-off-by: Miklos Vajna <vmiklos@frugalware.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

refs.c

@@ -964,14 +964,14 @@ int rename_ref(const char *oldref, const char *newref, const char *logmsg)
 	struct stat loginfo;
 	int log = !lstat(git_path("logs/%s", oldref), &loginfo);
 	const char *symref = NULL;
-	int is_symref = 0;
 
 	if (log && S_ISLNK(loginfo.st_mode))
 		return error("reflog for %s is a symlink", oldref);
 
 	symref = resolve_ref(oldref, orig_sha1, 1, &flag);
 	if (flag & REF_ISSYMREF)
-		is_symref = 1;
+		return error("refname %s is a symbolic ref, renaming it is not supported",
+			oldref);
 	if (!symref)
 		return error("refname %s not found", oldref);
 
@@ -1035,20 +1035,17 @@ int rename_ref(const char *oldref, const char *newref, const char *logmsg)
 	}
 	logmoved = log;
 
-	if (!is_symref) {
-		lock = lock_ref_sha1_basic(newref, NULL, 0, NULL);
-		if (!lock) {
-			error("unable to lock %s for update", newref);
-			goto rollback;
-		}
-		lock->force_write = 1;
-		hashcpy(lock->old_sha1, orig_sha1);
-		if (write_ref_sha1(lock, orig_sha1, logmsg)) {
-			error("unable to write current sha1 into %s", newref);
-			goto rollback;
-		}
-	} else
-		create_symref(newref, symref, logmsg);
+	lock = lock_ref_sha1_basic(newref, NULL, 0, NULL);
+	if (!lock) {
+		error("unable to lock %s for update", newref);
+		goto rollback;
+	}
+	lock->force_write = 1;
+	hashcpy(lock->old_sha1, orig_sha1);
+	if (write_ref_sha1(lock, orig_sha1, logmsg)) {
+		error("unable to write current sha1 into %s", newref);
+		goto rollback;
+	}
 
 	return 0;
 

t/t3200-branch.sh

@@ -112,13 +112,13 @@ test_expect_success 'config information was renamed, too' \
 	"test $(git config branch.s.dummy) = Hello &&
 	 test_must_fail git config branch.s/s/dummy"
 
-test_expect_success 'renaming a symref' \
+test_expect_success 'renaming a symref is not allowed' \
 '
 	git symbolic-ref refs/heads/master2 refs/heads/master &&
-	git branch -m master2 master3 &&
-	git symbolic-ref refs/heads/master3 &&
+	test_must_fail git branch -m master2 master3 &&
+	git symbolic-ref refs/heads/master2 &&
 	test -f .git/refs/heads/master &&
-	! test -f .git/refs/heads/master2
+	! test -f .git/refs/heads/master3
 '
 
 test_expect_success \