A non trivial example of where such a change would have consequences not captured by our tests (I think):

clinica/clinica/pipelines/anatomical/freesurfer/longitudinal/template/pipeline.py

Lines 37 to 40 in d379ae6

	image_ids = [
	re.search(r"(sub-[a-zA-Z0-9]+)_(long-[a-zA-Z0-9]+)", file).group()
	for file in t1_freesurfer_files
	]

Thanks for spotting that ! I can modify the regex depending on the separator we want to use. I made the modifications in the PR with "." but that might not be the best choice since it is widely used. We can also go with "+". WDYT ?