$ git clone -n https://src.fedoraproject.org/rpms/btrfs-progs.git /var/lib/mock/f41-build-841687-161335/root/chroot_tmpdir/scmroot/btrfs-progs
Cloning into '/var/lib/mock/f41-build-841687-161335/root/chroot_tmpdir/scmroot/btrfs-progs'...
$ git fetch origin 6c237214293435447e0c8d8e2b8a35629e8795a7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/btrfs-progs
 * [new ref]         6c237214293435447e0c8d8e2b8a35629e8795a7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6c23721 Delete upstreamed patch