Support Python patch version updates

[dougbu]

In completing #436, I realized the changes to the macos-python-3 artefact mean it will no-op when moving to a newer patch release of Python.

Specifically, https://dev.azure.com/dnceng/internal/_git/dotnet-helix-machines?path=/artifacts/macos-python-3/macos-python-3.sh ignores the patch version.

if [ $major -lt $requestedMajor ] || [ $minor -lt $requestedMinor ]; then

The above check will also work incorrectly if a machine already has (say) Python 4.0 on it when the requested version is 3.5.

I intentionally coded this to no-op when a Python installation was unnecessary. I unfortunately thought the patch version didn't matter much and didn't think the condition through thoroughly. However, Python patches frequently contain at least important-sounding fixes.

Release Note Category

• Feature changes/additions
• Bug fixes
• Internal Infrastructure Improvements

Release Note Description

Corrected a problem in the #436 fix to enable us to keep the installed Python version on OSX machines up to date w/ patch releases.

[dougbu]

/fyi @garath 😦

[dougbu]

!32884 is now merged. since this affects only OSX images as they're manually updated (nothing that rolls out on Wednesdays), we're done 😁

[dougbu]

not sure why I reopened this. bet I was confused…

[dougbu]

shoot. I can see clearly now. fix had to be reverted. will come back together w/ fix for #436

[dougbu]

together w/ #436 in one PR

[dougbu]

decided this isn't adding value being tracked separately from #436. it was a specific issue in an earlier try at a fix for that issue that was never actually complete