$ git clone -n https://src.fedoraproject.org/rpms/golang-modernc-gc-2.git /var/lib/mock/f42-build-866653-174013/root/chroot_tmpdir/scmroot/golang-modernc-gc-2
Cloning into '/var/lib/mock/f42-build-866653-174013/root/chroot_tmpdir/scmroot/golang-modernc-gc-2'...
$ git fetch origin 3dcc183b4f6e45a9a457d20cf0f568dbdce02585:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/golang-modernc-gc-2
 * [new ref]         3dcc183b4f6e45a9a457d20cf0f568dbdce02585 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3dcc183 Update to 2.6.1