[PATCH] "git branch -M @{-1}"

[Junio C Hamano <gitster@pobox.com>]

Earlier, we've taught "git branch -d <name>" that <name> is supposed to be
a branch name and not a random extended SHA-1.  "git branch -m <name> [<name>]" 
needs to be taught the same.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin-branch.c |   14 ++++++++++----
 1 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/builtin-branch.c b/builtin-branch.c
index c34af27..3f97838 100644
--- a/builtin-branch.c
+++ b/builtin-branch.c
@@ -425,21 +425,27 @@ static void rename_branch(const char *oldname, const char *newname, int force)
 	if (!oldname)
 		die("cannot rename the current branch while not on any.");
 
-	strbuf_addf(&oldref, "refs/heads/%s", oldname);
+	if (interpret_nth_last_branch(oldname, &oldref) == strlen(oldname))
+		strbuf_splice(&oldref, 0, 0, "refs/heads/", 11);
+	else
+		strbuf_addf(&oldref, "refs/heads/%s", oldname);
 
 	if (check_ref_format(oldref.buf))
 		die("Invalid branch name: %s", oldref.buf);
 
-	strbuf_addf(&newref, "refs/heads/%s", newname);
+	if (interpret_nth_last_branch(newname, &newref) == strlen(newname))
+		strbuf_splice(&newref, 0, 0, "refs/heads/", 11);
+	else
+		strbuf_addf(&newref, "refs/heads/%s", newname);
 
 	if (check_ref_format(newref.buf))
 		die("Invalid branch name: %s", newref.buf);
 
 	if (resolve_ref(newref.buf, sha1, 1, NULL) && !force)
-		die("A branch named '%s' already exists.", newname);
+		die("A branch named '%s' already exists.", newref.buf + 11);
 
 	strbuf_addf(&logmsg, "Branch: renamed %s to %s",
-		 oldref.buf, newref.buf);
+		    oldref.buf, newref.buf);
 
 	if (rename_ref(oldref.buf, newref.buf, logmsg.buf))
 		die("Branch rename failed");