sympy/sympy — pull request #7327 by amitsaha (2014-03-23 01:38:19+00:00)
Title: Point.is_collinear() should check for object types

This patch adds a minor fix to Point.is_collinear() so that if any other
geometric object is passed to it, it raises GeometryError.

For more background:
https://groups.google.com/forum/#!topic/sympy/vZxvnwemC4k