Changes to analysisOptions.ts

[DonJayamanne]

See here microsoft/python-language-server#1054 (comment)

[jakebailey]

At the top, it's:

this.envPythonPath = vars.PYTHONPATH || '';

But at the bottom, it's:

const envPythonPath = vars.PYTHONPATH;

if (this.envPythonPath !== envPythonPath) {
    this.didChange.fire();
}

So if vars.PYTHONPATH is undefined, then this.envPythonPath will be '', but envPythonPath will be undefined (hence why I think it's always firing).