I'm not at all clear on how these features should interact (alternation, non-greedy matching, and group capture).  Was just pointing that the first-match behavior of alternation is the documented behavior and that re.DEBUG can be used to explore what the regex is actually doing.   Whether this is correct, intended, desirable or consistent with other tools is a completely different question.  Even if not, there is a question about whether the behavior should be changed or just documented rather than risk breaking an untold number of regexes in already tested and deployed code.