pylint 2.16: raise a more intentional exception

Include a frivolous error message too. We never see it, but if someone
reads the code and wonders why on *earth* there's a DSL function to
raise a RuntimeError, the message string will clue them in.

mesonbuild/interpreter/interpreter.py

@@ -1393,7 +1393,7 @@ class Interpreter(InterpreterBase, HoldableObject):
     @noKwargs
     @noPosargs
     def func_exception(self, node, args, kwargs):
-        raise Exception()
+        raise RuntimeError('unit test traceback :)')
 
     def add_languages(self, args: T.List[str], required: bool, for_machine: MachineChoice) -> bool:
         success = self.add_languages_for(args, required, for_machine)