$ git clone -n https://src.fedoraproject.org/rpms/pythia8.git /var/lib/mock/f42-build-side-1-3578442-46814/root/chroot_tmpdir/scmroot/pythia8
Cloning into '/var/lib/mock/f42-build-side-1-3578442-46814/root/chroot_tmpdir/scmroot/pythia8'...
$ git fetch origin 2b3011628505624622139e67a6bf95b5ff9659ce:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/pythia8
 * [new ref]         2b3011628505624622139e67a6bf95b5ff9659ce -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2b30116 Update to version 8.3.15