TransformationArray.chain() doesnt return the expected rotation

[jpasserin]

In the following example the 3rd transform as an incorrect orientation. The Z axis isn't aligned with the chain plane
I think it must come from the parallelTransport()

from math3d.vectorN import Vector3, Vector3Array
from math3d.transformation import TransformationArray
from maya import cmds

positions = Vector3Array(
	[Vector3([-7.3,  7.7,  7.5]), 
	Vector3([-7.5, 13.4,  1.2]), 
	Vector3([-2.9,  8.2, -3.6 ]), 
	Vector3([-0.1,  3.9, -5.3])]
	)

normal = Vector3.planeNormal(*positions[:3])
chain = TransformationArray.chain(positions, normal=normal, axis="xz", negativeSide=False, endTransform=True)

for tfm in chain:
	loc = cmds.spaceLocator(name="pos1")
	cmds.xform(loc, matrix=tfm.asMatrix().flattened())