remote: only update remote-tracking branch if updating refspec

'git remote rename' will only update the remote's fetch refspec if it
looks like a default one. If the remote has no default fetch refspec,
as in

[remote "origin"]
    url = git://git.kernel.org/pub/scm/git/git.git
    fetch = +refs/heads/*:refs/remotes/upstream/*

we would not update the fetch refspec and even if there is a ref
called "refs/remotes/origin/master", we should not rename it, since it
was not created by fetching from the remote.

Suggested-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Martin von Zweigbergk <martin.von.zweigbergk@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/remote.c

@@ -635,7 +635,7 @@ static int mv(int argc, const char **argv)
 		old_remote_context = STRBUF_INIT;
 	struct string_list remote_branches = STRING_LIST_INIT_NODUP;
 	struct rename_info rename;
-	int i;
+	int i, refspec_updated = 0;
 
 	if (argc != 3)
 		usage_with_options(builtin_remote_rename_usage, options);
@@ -677,12 +677,13 @@ static int mv(int argc, const char **argv)
 		strbuf_reset(&buf2);
 		strbuf_addstr(&buf2, oldremote->fetch_refspec[i]);
 		ptr = strstr(buf2.buf, old_remote_context.buf);
-		if (ptr)
+		if (ptr) {
+			refspec_updated = 1;
 			strbuf_splice(&buf2,
 				      ptr-buf2.buf + strlen(":refs/remotes/"),
 				      strlen(rename.old), rename.new,
 				      strlen(rename.new));
-		else
+		} else
 			warning("Not updating non-default fetch respec\n"
 				"\t%s\n"
 				"\tPlease update the configuration manually if necessary.",
@@ -705,6 +706,9 @@ static int mv(int argc, const char **argv)
 		}
 	}
 
+	if (!refspec_updated)
+		return 0;
+
 	/*
 	 * First remove symrefs, then rename the rest, finally create
 	 * the new symrefs.

t/t5505-remote.sh

@@ -637,7 +637,8 @@ test_expect_success 'rename does not update a non-default fetch refspec' '
 	(cd four.one &&
 	 git config remote.origin.fetch +refs/heads/*:refs/heads/origin/* &&
 	 git remote rename origin upstream &&
-	 test "$(git config remote.upstream.fetch)" = "+refs/heads/*:refs/heads/origin/*")
+	 test "$(git config remote.upstream.fetch)" = "+refs/heads/*:refs/heads/origin/*" &&
+	 git rev-parse -q origin/master)
 
 '