$ git clone -n https://src.fedoraproject.org/rpms/gitg.git /var/lib/mock/f42-build-60946436-6586579/root/chroot_tmpdir/scmroot/gitg
Cloning into '/var/lib/mock/f42-build-60946436-6586579/root/chroot_tmpdir/scmroot/gitg'...
$ git fetch origin a6ea55aeade763007addecc7d145d3f9dabc3b47:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gitg
 * [new ref]         a6ea55aeade763007addecc7d145d3f9dabc3b47 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a6ea55a fix version