Caused by a060e96103
This change restores the old behavior of pass name detection from
channel name prior to the offending commit.
The fix includes regression test based on the files from related
reports, to help catching possible issues in the future.
Being so close to the release this commit restored behavior prior
to the previous fix. Potentially this makes some files to detect
wrong pass name for some specific files, although it is not really
clear if such files exists in the wild.
Pull Request: https://projects.blender.org/blender/blender/pulls/124458