$ git clone -n https://github.com/xcp-ng-rpms/libtasn1 /var/lib/mock/v8.3-u-pcoval2-10902-29396/root/chroot_tmpdir/scmroot/libtasn1
Cloning into '/var/lib/mock/v8.3-u-pcoval2-10902-29396/root/chroot_tmpdir/scmroot/libtasn1'...
$ git fetch origin b5f6c6e1768ad5da66818605da35e76fb2a19a08:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/libtasn1
 * [new ref]         b5f6c6e1768ad5da66818605da35e76fb2a19a08 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b5f6c6e bump release for test build