$ git clone -n https://src.fedoraproject.org/rpms/python-btrfs.git /var/lib/mock/f45-build-29853-641/root/chroot_tmpdir/scmroot/python-btrfs
Cloning into '/var/lib/mock/f45-build-29853-641/root/chroot_tmpdir/scmroot/python-btrfs'...
$ git fetch origin 584d7903501787a61475f7c8d43e26554cff3079:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/python-btrfs
 * [new ref]         584d7903501787a61475f7c8d43e26554cff3079 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 584d790 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild