$ git clone -n https://github.com/xcp-ng-rpms/ssmtp /var/lib/mock/v8.3-incoming-10676-29226/root/chroot_tmpdir/scmroot/ssmtp
Cloning into '/var/lib/mock/v8.3-incoming-10676-29226/root/chroot_tmpdir/scmroot/ssmtp'...
$ git fetch origin 89bbcb18ae94ed26185456a6ed93e75282f896b9:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/ssmtp
 * [new ref]         89bbcb18ae94ed26185456a6ed93e75282f896b9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 89bbcb1 Merge pull request #1 from xcp-ng-rpms/8.3-XS-1557