the `tag_gen()` function in github.py looks for tags using a regex:
match = re.search('([0-9.]+)', tag_data['name'])
if match:
yield match.groups()[0], tag_data

what this does is ignore versions like "251rc1" and changes them to "251", leaving a mismatched ebuild <-> package versions, causing failures.

Replacing those three lines above with the following three lines:
version = packaging.version.parse(tag_data['name'])
if version:
yield version, tag_data

This results in an accurate version parsing for tag_data. Note that the return function would then be simply:

return max(versions_and_tag_elements)

Patch attached.

Use case: This would now enable e.g. the systemd-tmpfiles package to use the tag_gen() command instead of creating its own tags searcher function