$ git clone -n https://src.fedoraproject.org/rpms/librepo.git /var/lib/mock/f40-build-2672704-67538/root/chroot_tmpdir/scmroot/librepo
Cloning into '/var/lib/mock/f40-build-2672704-67538/root/chroot_tmpdir/scmroot/librepo'...
$ git fetch origin e4daa90d0fe3a3a2ef7a65446fb4db55002f1121:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/librepo
 * [new ref]         e4daa90d0fe3a3a2ef7a65446fb4db55002f1121 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e4daa90 Update to 1.17.1