Message 65665 - Python tracker

webbrowser.py ignores browsers listed in the BROWSER environment
variables if it doesn't recognize the browser. For example, if I add
"links2" to the BROWSER env var, webbrowser.py ignores it.

It is because _synthesize() doesn't know how to handle an unknown
browser. The attached patch checks if _synthesize() doesn't register a
browser and registers a GenericBrowser.

Another approach would be to register GenericBrowser in _synthesize().