Comment 10 for bug 1437930

No, this is not the cause.
This is a bug in boost::polygon which happens rarely, and depends on the shape of polygons.

When using a value which differs from 16 to approximate circles by polygons, it happens less frequently, but it happens.

In this case, because most of polygons do not have 16 segments, and your patch (I tested it) has no effect.

Usually, just slightly changing a parameter (for instance zone clearance) modify the polygon shapes and avoid the crash.