bioformats misinterprets some nd files as HCS data if the stage labels match [a-z]\d+

[anntzer]

Consider the test nd dataset provided at #4069 (comment). Fiji's bio-formats importer opens it correctly, and inspecting it e.g. with showinf indicates Series count = 2 and Image count = 4 on both series, as expected.
Yet, if one opens test.nd and directly edits the position names from "position_a" and "position_b" to e.g. "f1" and "f2", then the dataset is no longer loaded correctly by Fiji (in particular it seems that some of the tiff files just don't show up at all in the final dataset), and showinf reports Series count = 2 but Image count = 1, together with a "RGB mismatch" warning. As far as I can see, this occurs because the position names match WELL_COORDS ("\\b([a-z])(\\d+)"), ultimately leading to taking the isHCS = true branch.
I can understand that some degree of guessing based on filenames and position names is needed, but I would guess that the isHCS = true branch could be skipped if 1) it leads to ignoring timepoints that are specified by the NTimePoints entry in the .nd file (and that are actually present), and/or 2) if it leads to RGB mismatched data (whereas the non-HCS interpretation is just fine).

[dgault]

Thank you @anntzer for opening the issue and investigating the root cause, that is extremely helpful. This is perhaps something we can look at addressing alongside #4069 at the same time