$ git clone -n https://src.fedoraproject.org/rpms/python-pynacl.git /var/lib/mock/f40-build-2231838-53312/root/chroot_tmpdir/scmroot/python-pynacl
Cloning into '/var/lib/mock/f40-build-2231838-53312/root/chroot_tmpdir/scmroot/python-pynacl'...
$ git fetch origin ba3c739ab622d1ec7e339c73af0d08e86002d49c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/python-pynacl
 * [new ref]         ba3c739ab622d1ec7e339c73af0d08e86002d49c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ba3c739 rebuild for new libsodium