If you run the following pipeline with lazy resampling it breaks as the pending info contains a 3x3 affine transform and there are 4x4 affine transforms already in the list:

[Flip(0), Flip(1), Rotate90(1), Zoom(0.8), NormalizeIntensity()]

Although it could be fixed by ensuring that Zoom always puts out a 4x4 affine, the more flexible and pragmatic solution is to promote 2d affine transforms to 3d affine transforms as a matter of course. This way we never have the issue that a given transform (particularly potential 3rd party transforms modified for lazy execution) can subsequently cause this problem.

Description

A few sentences describing the changes proposed in this pull request.

Types of changes

• Non-breaking change (fix or new feature that would not break existing functionality).
• Breaking change (fix or new feature that would cause existing functionality to change).
• New tests added to cover the changes.
• Integration tests passed locally by running ./runtests.sh -f -u --net --coverage.
• Quick tests passed locally by running ./runtests.sh --quick --unittests --disttests.
• In-line docstrings updated.
• Documentation updated, tested make html command in the docs/ folder.