Issue reading an LTA generated by fMRIPrep

[oesteban]

This LTA file (generated by this node) fails to load:

>>> import nitransforms as nit
>>> xfm = nit.linear.load('T1_robustreg.lta', fmt='lta')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/oesteban/workspace/nitransforms/nitransforms/linear.py", line 455, in load
    filename, fmt=fmt, reference=reference, moving=moving
  File "/home/oesteban/workspace/nitransforms/nitransforms/linear.py", line 198, in from_filename
    return cls(matrix, reference=reference)
  File "/home/oesteban/workspace/nitransforms/nitransforms/linear.py", line 236, in __init__
    for xfm in transforms
  File "/home/oesteban/workspace/nitransforms/nitransforms/linear.py", line 236, in <listcomp>
    for xfm in transforms
  File "/home/oesteban/workspace/nitransforms/nitransforms/linear.py", line 70, in __init__
    raise ValueError("Matrix does not represent a valid transform.")
ValueError: Matrix does not represent a valid transform.

[oesteban]

BTW - that transform, as per fMRIPrep, translates to ITK as this file - we should add a test checking idempotence (i.e., lta <-> itk <-> lta).

[oesteban]

It seems this is still failing at "/home/oesteban/workspace/nitransforms/nitransforms/linear.py", line 70.