$ git clone -n https://src.fedoraproject.org/rpms/kf6-kwindowsystem.git /var/lib/mock/f42-build-side-1-3583709-46890/root/chroot_tmpdir/scmroot/kf6-kwindowsystem
Cloning into '/var/lib/mock/f42-build-side-1-3583709-46890/root/chroot_tmpdir/scmroot/kf6-kwindowsystem'...
$ git fetch origin 49dcb637f67e8df3e2e6c9bc3a7303bd2dacbed0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/kf6-kwindowsystem
 * [new ref]         49dcb637f67e8df3e2e6c9bc3a7303bd2dacbed0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 49dcb63 6.16.0