$ git clone -n https://src.fedoraproject.org/rpms/gap-pkg-transgrp.git /var/lib/mock/f40-build-2095065-50372/root/chroot_tmpdir/scmroot/gap-pkg-transgrp
Cloning into '/var/lib/mock/f40-build-2095065-50372/root/chroot_tmpdir/scmroot/gap-pkg-transgrp'...
$ git fetch origin f5b177e3475769d8f9a0f3777d13ef2cbe32135e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gap-pkg-transgrp
 * [new ref]         f5b177e3475769d8f9a0f3777d13ef2cbe32135e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f5b177e Version 3.6.5