Test test_pointmanipulation.test_median_point failed only on Windows 64bits

[pradal]

Here is the error (see AppVeyor CI

======================================================================
ERROR: test_pointmanipulation.test_median_point

Traceback (most recent call last):
File "C:\Miniconda\conda-bld\openalea.plantgl_1518250173049_test_env\lib\site-packages\nose\case.py", line 197, in runTest
self.test(*self.arg)
File "C:\Miniconda\conda-bld\openalea.plantgl_1518250173049\test_tmp\test\test_pointmanipulation.py", line 34, in test_median_point
raise ValueError(k,j,dist_to_points(p3list[i],p3list),dist_to_points(p3list[j],p3list),p3list[i],p3list[j])
ValueError: (80, 99, 5300.545823832321, 5300.545823832321, Vector3(69.4804,61.5419,47.4436), Vector3(69.4804,61.5419,47.4436))

Ran 131 tests in 12.093s