$ git clone -n https://src.fedoraproject.org/rpms/plasma-mobile.git /var/lib/mock/f42-build-side-1-3578418-46814/root/chroot_tmpdir/scmroot/plasma-mobile
Cloning into '/var/lib/mock/f42-build-side-1-3578418-46814/root/chroot_tmpdir/scmroot/plasma-mobile'...
$ git fetch origin f8049395a7b0efa558aec5fd9b4731a7414e6be0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/plasma-mobile
 * [new ref]         f8049395a7b0efa558aec5fd9b4731a7414e6be0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f804939 6.4.1