$ git clone -n https://src.fedoraproject.org/rpms/python-BTrees.git /var/lib/mock/f40-build-730697-103596/root/chroot_tmpdir/scmroot/python-BTrees
Cloning into '/var/lib/mock/f40-build-730697-103596/root/chroot_tmpdir/scmroot/python-BTrees'...
$ git fetch origin 222b96665d1c1db6592ac914308dc45e39d9ad5f:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/python-BTrees
 * [new ref]         222b96665d1c1db6592ac914308dc45e39d9ad5f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 222b966 Version 5.1