$ git clone -n https://src.fedoraproject.org/rpms/copr-backend.git /var/lib/mock/f38-build-side-42-init-devel-622633-26353/root/chroot_tmpdir/scmroot/copr-backend
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-622633-26353/root/chroot_tmpdir/scmroot/copr-backend'...
$ git fetch origin b39b7708f325e58c7580d5cf342fdfbff2adf189:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/copr-backend
 * [new ref]         b39b7708f325e58c7580d5cf342fdfbff2adf189 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b39b770 Update copr-backend to 1.168-1