remote: write correct fetch spec when renaming remote 'remote'

When renaming a remote whose name is contained in a configured fetch
refspec for that remote, we currently replace the first occurrence of
the remote name in the refspec. This is correct in most cases, but
breaks if the remote name occurs in the fetch refspec before the
expected place. For example, we currently change

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

into

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

Reduce the risk of changing incorrect sections of the refspec by
matching the entire ":refs/remotes/<name>/" instead of just "<name>".

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

builtin/remote.c

@@ -631,7 +631,8 @@ static int mv(int argc, const char **argv)
 		OPT_END()
 	};
 	struct remote *oldremote, *newremote;
-	struct strbuf buf = STRBUF_INIT, buf2 = STRBUF_INIT, buf3 = STRBUF_INIT;
+	struct strbuf buf = STRBUF_INIT, buf2 = STRBUF_INIT, buf3 = STRBUF_INIT,
+		old_remote_context = STRBUF_INIT;
 	struct string_list remote_branches = STRING_LIST_INIT_NODUP;
 	struct rename_info rename;
 	int i;
@@ -669,15 +670,18 @@ static int mv(int argc, const char **argv)
 	strbuf_addf(&buf, "remote.%s.fetch", rename.new);
 	if (git_config_set_multivar(buf.buf, NULL, NULL, 1))
 		return error("Could not remove config section '%s'", buf.buf);
+	strbuf_addf(&old_remote_context, ":refs/remotes/%s/", rename.old);
 	for (i = 0; i < oldremote->fetch_refspec_nr; i++) {
 		char *ptr;
 
 		strbuf_reset(&buf2);
 		strbuf_addstr(&buf2, oldremote->fetch_refspec[i]);
-		ptr = strstr(buf2.buf, rename.old);
+		ptr = strstr(buf2.buf, old_remote_context.buf);
 		if (ptr)
-			strbuf_splice(&buf2, ptr-buf2.buf, strlen(rename.old),
-					rename.new, strlen(rename.new));
+			strbuf_splice(&buf2,
+				      ptr-buf2.buf + strlen(":refs/remotes/"),
+				      strlen(rename.old), rename.new,
+				      strlen(rename.new));
 		if (git_config_set_multivar(buf.buf, buf2.buf, "^$", 0))
 			return error("Could not append '%s'", buf.buf);
 	}

t/t5505-remote.sh

@@ -631,6 +631,26 @@ test_expect_success 'rename a remote' '
 
 '
 
+test_expect_success 'rename does not update a non-default fetch refspec' '
+
+	git clone one four.one &&
+	(cd four.one &&
+	 git config remote.origin.fetch +refs/heads/*:refs/heads/origin/* &&
+	 git remote rename origin upstream &&
+	 test "$(git config remote.upstream.fetch)" = "+refs/heads/*:refs/heads/origin/*")
+
+'
+
+test_expect_success 'rename a remote with name part of fetch spec' '
+
+	git clone one four.two &&
+	(cd four.two &&
+	 git remote rename origin remote &&
+	 git remote rename remote upstream &&
+	 test "$(git config remote.upstream.fetch)" = "+refs/heads/*:refs/remotes/upstream/*")
+
+'
+
 cat > remotes_origin << EOF
 URL: $(pwd)/one
 Push: refs/heads/master:refs/heads/upstream