Wrong variable in Vector2.set_y routine

[GoogleCodeExporter]

code is currently:

def set_y(self, y):
        assert isinstance(x, float), "Must be a float"

and should be this:

def set_y(self, y):
        assert isinstance(y, float), "Must be a float"

Original issue reported on code.google.com by jmric...@gmail.com on 7 Feb 2013 at 11:05