$ git clone -n https://src.fedoraproject.org/rpms/fbrnch.git /var/lib/mock/f39-build-1965410-43292/root/chroot_tmpdir/scmroot/fbrnch
Cloning into '/var/lib/mock/f39-build-1965410-43292/root/chroot_tmpdir/scmroot/fbrnch'...
$ git fetch origin 2f99f693b3205b8c239770e1b3940c246824061b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/fbrnch
 * [new ref]         2f99f693b3205b8c239770e1b3940c246824061b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2f99f69 update to 1.3.3