Update python version regex and fix version ordering

[amazimbe]

What are you trying to accomplish?

Link to issue
Update our python version implementation to be conformant with the python version specification here: https://peps.python.org/pep-0440/#appendix-b-parsing-version-strings-with-regular-expressions

I'm updating the regex for version formats to be the one specified in the python version specification.

Anything you want to highlight for special attention from reviewers?

How will you know you've accomplished your goal?

Checklist

• I have run the complete test suite to ensure all tests and linters pass.
• I have thoroughly tested my code changes to ensure they work as expected, including adding additional tests for new functionality.
• I have written clear and descriptive commit messages.
• I have provided a detailed description of the changes in the pull request, including the problem it addresses, how it fixes the problem, and any relevant details about the implementation.
• I have ensured that the code is well-documented and easy to understand.

[kbukum1]

Is there a merged python regex update changes related to this test cases? Or this is refining the test cases? I couldn't see the regex changes here?

[amazimbe]

Is there a merged python regex update changes related to this test cases? Or this is refining the test cases? I couldn't see the regex changes here?

It's coming. It's got python regex features and converting those to ruby has been problematic so far.

VERSION_PATTERN = r"""
    v?
    (?:
        (?:(?P<epoch>[0-9]+)!)?                           # epoch
        (?P<release>[0-9]+(?:\.[0-9]+)*)                  # release segment
        (?P<pre>                                          # pre-release
            [-_\.]?
            (?P<pre_l>(a|b|c|rc|alpha|beta|pre|preview))
            [-_\.]?
            (?P<pre_n>[0-9]+)?
        )?
        (?P<post>                                         # post release
            (?:-(?P<post_n1>[0-9]+))
            |
            (?:
                [-_\.]?
                (?P<post_l>post|rev|r)
                [-_\.]?
                (?P<post_n2>[0-9]+)?
            )
        )?
        (?P<dev>                                          # dev release
            [-_\.]?
            (?P<dev_l>dev)
            [-_\.]?
            (?P<dev_n>[0-9]+)?
        )?
    )
    (?:\+(?P<local>[a-z0-9]+(?:[-_\.][a-z0-9]+)*))?       # local version
"""

[pavera]

I think this looks good in general. My only concern is I'm not sure how widespread adherence to this standard is across the python community. Projects which deviate, but were "allowed" under the old regex will now fail to get updates.

[amazimbe]

I think this looks good in general. My only concern is I'm not sure how widespread adherence to this standard is across the python community. Projects which deviate, but were "allowed" under the old regex will now fail to get updates.

Thanks @pavera . I'll add your concern to the discussion but so far I haven't encountered a version that was valid under the previous regex that is no longer valid under the new regex.

[amazimbe]

@pavera I've had to add a feature flag, in case, things go wrong after deploying. It's mostly code that I'll clean up soon after deploying but do let me know if you have any additional feedback.