$ git clone -n https://github.com/xcp-ng-rpms/ssmtp.git /var/lib/mock/v8.3-u-pcoval2-10059-28695/root/chroot_tmpdir/scmroot/ssmtp
Cloning into '/var/lib/mock/v8.3-u-pcoval2-10059-28695/root/chroot_tmpdir/scmroot/ssmtp'...
$ git fetch origin 90da4f764341c6238a0e3a813a9dbb3930491045:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/ssmtp
 * [new ref]         90da4f764341c6238a0e3a813a9dbb3930491045 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 90da4f7 bump release for test build