$ git clone -n https://github.com/xcp-ng-rpms/libtasn1 /var/lib/mock/v8.3-u-pcoval1-11075-29510/root/chroot_tmpdir/scmroot/libtasn1
Cloning into '/var/lib/mock/v8.3-u-pcoval1-11075-29510/root/chroot_tmpdir/scmroot/libtasn1'...
$ git fetch origin b34b6110f4ba4b0c9363016ec2694e797c621602:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/libtasn1
 * [new ref]         b34b6110f4ba4b0c9363016ec2694e797c621602 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b34b611 bump release for test build