$ git clone -n https://src.fedoraproject.org/rpms/plasma-desktop.git /var/lib/mock/f42-bootstrap-3533709-46421/root/chroot_tmpdir/scmroot/plasma-desktop
Cloning into '/var/lib/mock/f42-bootstrap-3533709-46421/root/chroot_tmpdir/scmroot/plasma-desktop'...
$ git fetch origin 6a93677f374655905c0176c5f73d7cde8f2b622a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/plasma-desktop
 * [new ref]         6a93677f374655905c0176c5f73d7cde8f2b622a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6a93677 6.3.5