$ git clone -n https://src.fedoraproject.org/rpms/golang-gopkg-stack-0.git /var/lib/mock/f41-build-1036609-18741/root/chroot_tmpdir/scmroot/golang-gopkg-stack-0
Cloning into '/var/lib/mock/f41-build-1036609-18741/root/chroot_tmpdir/scmroot/golang-gopkg-stack-0'...
$ git fetch origin 65c49b5d3098c182aa0543249c4d5fb67d29a147:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/golang-gopkg-stack-0
 * [new ref]         65c49b5d3098c182aa0543249c4d5fb67d29a147 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 65c49b5 Fix FTBFS