$ git clone -n https://src.fedoraproject.org/rpms/nanopb.git /var/lib/mock/f39-build-1586096-38177/root/chroot_tmpdir/scmroot/nanopb
Cloning into '/var/lib/mock/f39-build-1586096-38177/root/chroot_tmpdir/scmroot/nanopb'...
$ git fetch origin c12864951b7c6bec1d25be49418df65e62fff324:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/nanopb
 * [new ref]         c12864951b7c6bec1d25be49418df65e62fff324 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c128649 remove python2 related files