$ git clone -n https://src.fedoraproject.org/rpms/xcompmgr.git /var/lib/mock/f45-build-38679-727/root/chroot_tmpdir/scmroot/xcompmgr
Cloning into '/var/lib/mock/f45-build-38679-727/root/chroot_tmpdir/scmroot/xcompmgr'...
$ git fetch origin dc89f8b35f1543c3c199482519255b3a09a57928:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/xcompmgr
 * [new ref]         dc89f8b35f1543c3c199482519255b3a09a57928 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at dc89f8b Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild