The motion tracking always operates with horizontal sensor mapping, but
conversion code form tracking camera to Blender camera was not setting
the sensor fitting to Horizontal (Python code was leaving sensor fitting
unchanged, C code was setting it to Auto).
Additionally, the Python code was not handling camera shift, making it
so non-centered optical center was not handled correctly.
The reason why the code is written in two places is because C code is
used when conversion from tracking camera to Blender happens after solving
the motion, and the Python code is used for the "Setup Tracking Scene".
It is possible to unify some code, but it is not that much of an importance
at this time.
Pull Request: https://projects.blender.org/blender/blender/pulls/114253
d7b7938706