Wrong work if y data are equal

[tantra35]

If we ran follow script

import simplify

print simplify.simplify_points([{'y': 0, 'x': 15}, {'y': 0.6, 'x': 16}, {'y': 0, 'x': 17}], 0.5)

we got:

[{'y': 0, 'x': 15}, {'y': 0.6, 'x': 16}, {'y': 0, 'x': 17}]

But this is wrong, we must get follow result:

[{'y': 0, 'x': 15}, {'y': 0, 'x': 17}]