$ git clone -n https://github.com/xcp-ng-rpms/libevent /var/lib/mock/v8.3-incoming-9891-28597/root/chroot_tmpdir/scmroot/libevent
Cloning into '/var/lib/mock/v8.3-incoming-9891-28597/root/chroot_tmpdir/scmroot/libevent'...
$ git fetch origin 93e08926257df557c6e736ecd6e9fbb06b2a6eff:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/libevent
 * [new ref]         93e08926257df557c6e736ecd6e9fbb06b2a6eff -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 93e0892 spec: Bump release