LINEARRING confuses Line Overlay

[pramsey]

Running the existing XML tests using SnapIfNecessary (aka, making OverlayNG the default overlay implementation) and this case is an interesting failure.

	Description: GC - shows handling linear rings and linestrings
	Geometry A: GEOMETRYCOLLECTION (LINEARRING (0 0, 0 70, 80 70, 80 0, 0 0), LINESTRING (30 110, 30 30, 100 30))
	Expected result: MULTILINESTRING ((0 0, 0 70, 30 70), (30 70, 80 70, 80 30), (80 30, 80 0, 0 0), (30 110, 30 70), (30 70, 30 30, 80 30), (80 30, 100 30))
	Obtained result: LINESTRING (30 110, 30 30, 100 30)

When you change the input A from a LINEARRING to a LINESTRING the failure goes away. There's at least one other LINEARRING failure case in GEOS XML test suite, but this one seems good and illustrative.

[dr-jts]

That is a test of UnaryUnion, in case not clear.

JTS produces the expected result using OverlayNG UnaryUnion (either called directly, or as part of OverlayNGSnapIfNeeded - not surprising, since there is no snapping invoked for this case).

So it looks like this might be a GEOS-only thing?

[pramsey]

Damn.