STYLE enable pylint: undefined-variable

[natmokval]

Issue #48855. This PR enables pylint warning: undefined-variable

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[natmokval]

To fix the warning I had to refactor the function determine_clipboard(). Hopefully, I did it the right way.

[MarcoGorelli]

thanks for looking into this!

not sure about returning init_osx_pbcopy_clipboard within init_osx_pyobjc_clipboard

I think pylint might not be correct here, e.g. if we have

def foo():
    print(re)

def bar():
    global re
    try:
        import re
    except ImportError:
        pass
    else:
        foo()

bar()

then it executes just fine

Shall just keep as-is and turn off the warning?

[natmokval]

Thanks, @MarcoGorelli for the example. Sure thing, let’s keep this warning turn off.