Currently fixup_unbounded_boxes assumes that the extents are tight when we only
have one box. This is not always true. e.g. when we tesselate boxes we can end
up with only one box which is smaller than the extents and the extents are not
updated.
--HG--
extra : rebase_source : 5e01da7d845c1cd34f9e87d5c7de22dafe9df7a4
