$ git clone -n https://src.fedoraproject.org/rpms/thunderbird.git /var/lib/mock/f41-build-side-1-3136300-39772/root/chroot_tmpdir/scmroot/thunderbird
Cloning into '/var/lib/mock/f41-build-side-1-3136300-39772/root/chroot_tmpdir/scmroot/thunderbird'...
$ git fetch origin 85ee6eef50e98ea21a53c8ee2328c0a6e0be1ad0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/thunderbird
 * [new ref]         85ee6eef50e98ea21a53c8ee2328c0a6e0be1ad0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 85ee6ee Update to 128.4.3