$ git clone -n https://src.fedoraproject.org/rpms/golang-github-docker.git /var/lib/mock/f40-build-2239071-53593/root/chroot_tmpdir/scmroot/golang-github-docker
Cloning into '/var/lib/mock/f40-build-2239071-53593/root/chroot_tmpdir/scmroot/golang-github-docker'...
$ git fetch origin 3a9e3c019fc4fad05998c520568c7d461973641a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/golang-github-docker
 * [new ref]         3a9e3c019fc4fad05998c520568c7d461973641a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3a9e3c0 Remove deprecated %patchN syntax