of its segs thrown away, so the map could not start. This was because the
nodebuilder assumed all subsectors would be 2D and could not handle the
case where a degenerate 1D subsector is created. In this case, that happens
because that map has three polyobjects in the middle of the void, so the only
way to assign them to a subsector is to use a 1D subsector.
SVN r153 (trunk)