$ git clone -n https://src.fedoraproject.org/rpms/golang-github-siddontang-snappy.git /var/lib/mock/f41-build-1036367-18724/root/chroot_tmpdir/scmroot/golang-github-siddontang-snappy
Cloning into '/var/lib/mock/f41-build-1036367-18724/root/chroot_tmpdir/scmroot/golang-github-siddontang-snappy'...
$ git fetch origin 91ce3fedd74a8c2d89f7b5b9d7744f62f76e66c5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/golang-github-siddontang-snappy
 * [new ref]         91ce3fedd74a8c2d89f7b5b9d7744f62f76e66c5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 91ce3fe Fix FTBFS