$ git clone -n https://src.fedoraproject.org/rpms/gnome-usage.git /var/lib/mock/f42-build-side-1-3498505-45962/root/chroot_tmpdir/scmroot/gnome-usage
Cloning into '/var/lib/mock/f42-build-side-1-3498505-45962/root/chroot_tmpdir/scmroot/gnome-usage'...
$ git fetch origin c5d5e64837724189c17a550bde2f34200b520e55:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gnome-usage
 * [new ref]         c5d5e64837724189c17a550bde2f34200b520e55 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c5d5e64 Rebuilt