Method prepend_to

tests/debug/config.py:222–230

Prepends a new entry to a PATH-style environment variable, creating it if it doesn't exist already.

(self, key, entry)

            return dict(self)

        def prepend_to(self, key, entry):
            """Prepends a new entry to a PATH-style environment variable, creating
            it if it doesn't exist already.
            """
            try:
                tail = os.path.pathsep + self[key]
            except KeyError:
                tail = ""
            self[key] = entry + tail

    class DebugOptions(MutableSet):
        """Wraps config["debugOptions"], automatically creating and destroying it as