Access to original_message is not thread-safe

[Alerion]

This code is not thread-safe:

global original_message
original_message = original_msg
result = method(*args, **kwargs)
original_message = None

If you have two JsonRpcWebsocketConsumer you can get a moment, when one thread reset original_message and other tries to read it.

[Alerion]

Possible solution to pass original messages if method expects this argument:

func_args, _, _, _ = getargspec(method)
if 'original_msg' in func_args:
    kwargs['original_msg'] = original_message
result = method(*args, **kwargs)

[millerf]

I am not a great fan of forcing the value of a parameter based on its name... I will try to find a better way...
At the moment I am also trying to create a test that shows the problem. And I am having a hard time :)