remote: make guess_remote_head() use exact HEAD lookup if it is available

peff · gitster · commit fbb074c25352 · 2009-02-27T15:19:23.000-08:00
Our usual method for determining the ref pointed to by HEAD
is to compare HEAD's sha1 to the sha1 of all refs, trying to
find a unique match.

However, some transports actually get to look at HEAD
directly; we should make use of that information when it is
available.  Currently, only http remotes support this
feature.

Signed-off-by: Jeff King &lt;peff@peff.net&gt;
Signed-off-by: Jay Soffian &lt;jaysoffian@gmail.com&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
diff --git a/remote.c b/remote.c
@@ -1476,6 +1476,14 @@ struct ref *guess_remote_head(const struct ref *head,
 	if (!head)
 		return NULL;
 
+	/*
+	 * Some transports support directly peeking at
+	 * where HEAD points; if that is the case, then
+	 * we don't have to guess.
+	 */
+	if (head->symref)
+		return copy_ref(find_ref_by_name(refs, head->symref));
+
 	/* If refs/heads/master could be right, it is. */
 	if (!all) {
 		r = find_ref_by_name(refs, "refs/heads/master");
diff --git a/t/t5550-http-fetch.sh b/t/t5550-http-fetch.sh
@@ -42,5 +42,16 @@ test_expect_success 'fetch changes via http' '
 	test_cmp file clone/file
 '
 
+test_expect_success 'http remote detects correct HEAD' '
+	git push public master:other &&
+	(cd clone &&
+	 git remote set-head origin -d &&
+	 git remote set-head origin -a &&
+	 git symbolic-ref refs/remotes/origin/HEAD > output &&
+	 echo refs/remotes/origin/master > expect &&
+	 test_cmp expect output
+	)
+'
+
 stop_httpd
 test_done
