Sync with 1.7.6.1

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git.txt

@@ -44,9 +44,10 @@ unreleased) version of git, that is available from 'master'
 branch of the `git.git` repository.
 Documentation for older releases are available here:
 
-* link:v1.7.6/git.html[documentation for release 1.7.6]
+* link:v1.7.6.1/git.html[documentation for release 1.7.6.1]
 
 * release notes for
+  link:RelNotes/1.7.6.1.txt[1.7.6.1].
   link:RelNotes/1.7.6.txt[1.7.6].
 
 * link:v1.7.5.4/git.html[documentation for release 1.7.5.4]

upload-pack.c

@@ -533,6 +533,8 @@ static void check_non_tip(void)
 	namebuf[41] = '\n';
 	for (i = get_max_object_index(); 0 < i; ) {
 		o = get_indexed_object(--i);
+		if (!o)
+			continue;
 		if (!(o->flags & OUR_REF))
 			continue;
 		memcpy(namebuf + 1, sha1_to_hex(o->sha1), 40);