$ git clone -n https://src.fedoraproject.org/rpms/golang-github-google-martian.git /var/lib/mock/f40-build-2240925-53656/root/chroot_tmpdir/scmroot/golang-github-google-martian
Cloning into '/var/lib/mock/f40-build-2240925-53656/root/chroot_tmpdir/scmroot/golang-github-google-martian'...
$ git fetch origin 2c811a6a7e5a3294a1731cdb02caedcca2b4e23c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/golang-github-google-martian
 * [new ref]         2c811a6a7e5a3294a1731cdb02caedcca2b4e23c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2c811a6 Remove deprecated %patchN syntax