One issue here is that I could *potentially* see this going awry.  It's a simple enough pattern that I could see it occurring in the changelog in contexts that are not issue numbers.  As the issue references in the changelog only occur inside square brackets I might update to only look for them there.

There are a few cases where many issues are mentioned inside one pair of brackets, so there should be a regexp that searches for something like `r'\[#.*\]` (it would have to be a multi-line regexp as well) and then searches within any match of that pattern for `r'#\d+'`.  Unfortunately I don't think it could be handled by a single regular expression since the `re` module does not support repeated capture groups.