Don’t call didReceiveError twice if deadline is exceeded and request is canceled afterwards

[dnadoba]

Motivation

If the deadline is exceeded and the connection state machine fails the request with an error, we forgot to transition to the finished state in the RequestBag. A symptom of this is that a request could afterwards still be canceled from user code and it would trigger a second call to the delegates didRecieveError method.

Modification

• transition to the finished state
• add a test which fails without the change above

Result

didReceiveError can't be called twice