$ git clone -n https://src.fedoraproject.org/rpms/golang-github-prometheus-alertmanager.git /var/lib/mock/f40-build-2236521-53513/root/chroot_tmpdir/scmroot/golang-github-prometheus-alertmanager
Cloning into '/var/lib/mock/f40-build-2236521-53513/root/chroot_tmpdir/scmroot/golang-github-prometheus-alertmanager'...
$ git fetch origin 5e9166873d7229c815d17e8d1dea549757f6949f:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/golang-github-prometheus-alertmanager
 * [new ref]         5e9166873d7229c815d17e8d1dea549757f6949f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5e91668 Remove deprecated %patchN syntax