Adding explicit unlocking using portalocker

[abhidnya13]

Resolves #42

[abhidnya13]

https://github.com/AzureAD/microsoft-authentication-extensions-for-python/wiki/Default-timeout-and-retry-settings-for-locking-mechanisms

[rayluo]

Thank you @abhidnya13 ! Your effort on testing on Mac and founding the significance of that LOCK_NB flag saves us from a future bugfix!

[bluca]

@abhidnya13 @rayluo just to be sure, what happens on Linux if portalocker doesn't have the fix? Will something break, or will it be an issue only in Windows?

[rayluo]

@bluca According to #42, the specific issue, i.e. lock file is not being deleted, is only reported in Windows.

Did you observe any issue on Linux? If so, what is the symptom? Please create a new issue to describe it.

[bluca]

@bluca According to #42, the specific issue, i.e. lock file is not being deleted, is only reported in Windows.

Did you observe any issue on Linux? If so, what is the symptom? Please create a new issue to describe it.

I did not see any issue - I am wondering whether I need to enforce the dependency on Linux or not when uploading the new version to Debian/Ubuntu.

[rayluo]

@bluca If you are using this MSAL Extensions for Python library, it already enforces that dependency (on all platforms, for that matter). If you are using portalocker directly, you can make that decision. You may even open an issue in that repo and hear the input from its author, who is very responsive to github issues.

[bluca]

@bluca If you are using this MSAL Extensions for Python library, it already enforces that dependency (on all platforms, for that matter).

No, it doesn't - unless I make it. Hence the question - should it? Is it really necessary for Linux?