$ git clone -n https://src.fedoraproject.org/rpms/copr-backend.git /var/lib/mock/f42-build-3440427-45448/root/chroot_tmpdir/scmroot/copr-backend
Cloning into '/var/lib/mock/f42-build-3440427-45448/root/chroot_tmpdir/scmroot/copr-backend'...
$ git fetch origin c5116add30b0c37b6d617a6fc9504c19628a8a19:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/copr-backend
 * [new ref]         c5116add30b0c37b6d617a6fc9504c19628a8a19 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c5116ad Update copr-backend to 2.3-1