$ git clone -n https://src.fedoraproject.org/rpms/gcc.git /var/lib/mock/f40-build-807880-145348/root/chroot_tmpdir/scmroot/gcc
Cloning into '/var/lib/mock/f40-build-807880-145348/root/chroot_tmpdir/scmroot/gcc'...
$ git fetch origin 8e7867c2d3dbf7225ed0bbc8e17ad71cf2bbccbd:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gcc
 * [new ref]         8e7867c2d3dbf7225ed0bbc8e17ad71cf2bbccbd -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8e7867c 14.1.1-1