> Basically this comes down to the fuzziness of the FPzero/FPeq tests.
>
> It might be possible to fix this particular problem by changing the FPzero
> tests in line_parallel() to exact "== 0" tests; though we would likely
> be well advised to still keep the main test as FPeq.
That can create whole bunch of different problems, because then the
fuzziness wouldn't apply to the values around the zero. I don't think
there is any good solution without removing those macros all together.
We should just fix what is obviously broken for now.