GEOSCoordSeq_setX also sets y as a side-effect

[sgillies@…]

The GEOSCoordSeq_setY function does *not* have an effect on x.

I am seeing this with point (size=1) coordinate sequences. I have not yet tested other sequences.

Example code (using Python ctypes, which is pretty much exactly the same as programming in C):

cs = lgeos.GEOSCoordSeq_create(1, ndim)
# Setting X appears to clobber Y. Watch how the doctest above
# fails.
lgeos.GEOSCoordSeq_setY(cs, 0, dy)
lgeos.GEOSCoordSeq_setX(cs, 0, dx)