OAuth unauthorized errors mask the actual error text

[Julian Edwards]

If a Nonce is re-used, the maas log has this in it:

ERROR 2014-01-15 18:18:28,633 maasserver ################################ Exception: ################################
ERROR 2014-01-15 18:18:28,633 maasserver Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/django/core/handlers/base.py", line 115, in get_response
    response = callback(request, *callback_args, **callback_kwargs)
  File "/usr/lib/python2.7/dist-packages/django/views/decorators/vary.py", line 19, in inner_func
    response = func(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/piston/resource.py", line 128, in __call__
    actor, anonymous = self.authenticate(request, rm)
  File "/usr/lib/python2.7/dist-packages/maasserver/api_support.py", line 47, in authenticate
    RestrictedResource, self).authenticate(request, rm)
  File "/usr/lib/python2.7/dist-packages/piston/resource.py", line 103, in authenticate
    if not authenticator.is_authenticated(request):
  File "/usr/lib/python2.7/dist-packages/maasserver/api_auth.py", line 57, in is_authenticated
    raise OAuthUnauthorized(error)
OAuthUnauthorized

In addition the error returned to the client does not mention it's a nonce problem. It used to do this, so this is a regression.

I realise we have nonce-cleaning code now but this can still happen and it would save support time.