$ git clone -n https://github.com/xcp-ng-rpms/libevent /var/lib/mock/v8.3-incoming-9887-28597/root/chroot_tmpdir/scmroot/libevent
Cloning into '/var/lib/mock/v8.3-incoming-9887-28597/root/chroot_tmpdir/scmroot/libevent'...
$ git fetch origin 790f68962cf0e87e36ab44a9abf9bffb4b1d0c13:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/libevent
 * [new ref]         790f68962cf0e87e36ab44a9abf9bffb4b1d0c13 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 790f689 spec: Disable openssl on upstream el7.src.rpm