$ git clone -n https://src.fedoraproject.org/rpms/btrfs-progs.git /var/lib/mock/f41-build-828291-155703/root/chroot_tmpdir/scmroot/btrfs-progs
Cloning into '/var/lib/mock/f41-build-828291-155703/root/chroot_tmpdir/scmroot/btrfs-progs'...
$ git fetch origin d7985db5123915c79d795f0b03fdc605a36e0896:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/btrfs-progs
 * [new ref]         d7985db5123915c79d795f0b03fdc605a36e0896 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d7985db Update to 6.9.2