Comment 3 for bug 886118

OK, what happened here may be that the sudo prompt was accepted but on the *second* try (it would seem). This causes a desynchronization of messages because they get queued in a fifo. So:

- checkbox launches the backend and sends it a "ping".
- Backend does not start. After 30 seconds checkbox retries.
- checkbox launches the backend again and sends it a 'ping'.
- Backend launches, receives the first "ping" and sends back a "pong".
- checkbox receives the "pong" and continues the testing process, thinking it has a working backend.
- Backend notices the second "ping" and sends back a "pong" which stays in the pipe awaiting to be read.
- Checkbox sends the backend a job message and reads the backend's response, expecting it to be the message's result.
- Turns out the response was the second "pong". Things fail horribly from now on because backend and frontend are now out of sync.

This is a known problem that needs to be fixed, perhaps by adding a sequence number to commands so the frontend knows to discard or otherwise handle out-of-sequence messages.

My evidence:
2011-11-03 14:31:54,938 DEBUG Backend responded, continuing execution.
So we know the backend was running (at some point at least).

2011-11-04 09:06:29,663 DEBUG Calling /usr/share/checkbox/plugins/backend_info.py BackendInfo.message_exec({'status': 'uninitiated', 'command': 'cdimage_resource', 'user': 'root', 'name': 'cdimage', 'plugin': 'resource'}) for message-exec with priority 0.
2011-11-04 09:06:29,664 DEBUG Started firing message-result.
2011-11-04 09:06:29,665 DEBUG Calling /usr/share/checkbox/plugins/message_info.py MessageInfo.message_result(p, o, n, g) for message-result with priority 0.
2011-11-04 09:06:29,668 ERROR Error running event handler /usr/share/checkbox/plugins/message_info.py MessageInfo.message_result(p, o, n, g) for event type 'message-result'
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/checkbox/reactor.py", line 74, in fire
    results.append(handler(*args, **kwargs))
TypeError: message_result() takes exactly 4 arguments (5 given)

Notice the call to MessageInfo.message_result; the parameters spell "pong" :)

I'll set as Invalid for Ubuntu checkbox and Triaged/High for checkbox proper. It's the same code base after all, so no point on having two reports for the same thing.