$ git clone -n https://src.fedoraproject.org/rpms/nacl.git /var/lib/mock/f40-build-2242896-53669/root/chroot_tmpdir/scmroot/nacl
Cloning into '/var/lib/mock/f40-build-2242896-53669/root/chroot_tmpdir/scmroot/nacl'...
$ git fetch origin 75a90b3c87a741f1987331c7c16964e2b7810e5c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/nacl
 * [new ref]         75a90b3c87a741f1987331c7c16964e2b7810e5c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 75a90b3 Set build_type_safety_c to 0 (#2144813)