Handle backend being deleted during GetConfigOperation
Review Request #123860 - Created May 20, 2015 and submitted
GetConfigOperation stores a raw pointer to the backend in a property of the QDBusPendingCallWatcher BackendManager owns this backend and can delete it at will if it becomes invalidated, leaving a dangling pointer in the watcher's property. BUG: 347626
Never made the crash happen myself, but looking at the backtrace and the code it seems the a way it could have happened.
Tested behaviour as before still works.