Change the way we check for Android to use Python internals.

[rtibbles]

Summary

• Switches from the Python for Android specific environment variable checking to checking if an Android only sys call is present

References

https://docs.python.org/3/library/sys.html#sys.getandroidapilevel

Reviewer guidance

I have tested this in an Android installer build, and a call to this API returns the Android API version against which it was compiled (so the minimum API version of 23 that we currently support). This suggests to me this is a robust check, as it is not dependent on anything at runtime.

This should also allow for easier experimentation with a non-P4A based implementation like chaquopy in the future.

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Testing checklist

• Contributor has fully tested the PR manually
• If there are any front-end changes, before/after screenshots are included
• Critical user journeys are covered by Gherkin stories
• Critical and brittle code paths are covered by unit tests

PR process

• PR has the correct target branch and milestone
• PR has 'needs review' or 'work-in-progress' label
• If PR is ready for review, a reviewer has been added. (Don't use 'Assignees')
• If this is an important user-facing change, PR or related issue has a 'changelog' label
• If this includes an internal dependency change, a link to the diff is provided

Reviewer checklist

• Automated test coverage is satisfactory
• PR is fully functional
• PR has been tested for accessibility regressions
• External dependency files were updated if necessary (yarn and pip)
• Documentation is updated
• Contributor is in AUTHORS.md

[github-actions]

Build Artifacts

Asset type	Download link
PEX file	kolibri-0.16.0b1.dev0_git.44.g1200475d.pex
Windows Installer (EXE)	kolibri-0.16.0b1.dev0+git.44.g1200475d-unsigned.exe
Debian Package	kolibri_0.16.0b1.dev0+git.44.g1200475d-0ubuntu1_all.deb
Mac Installer (DMG)	kolibri-0.16.0b1.dev0+git.44.g1200475d-0.3.0.dmg
TAR file	kolibri-0.16.0b1.dev0+git.44.g1200475d.tar.gz
WHL file	kolibri-0.16.0b1.dev0+git.44.g1200475d-py2.py3-none-any.whl

[marcellamaki]

chatted through changes with richard - following that, lgtm!