Part of lp.bugs.interfaces
| Class | BugWatchActivityStatus | An enumeration of possible BugWatch errors. |
| Interface | IBugWatchSet | The set of `IBugWatch`es. |
| Class | NoBugTrackerFound | No bug tracker with the base_url is registered in Launchpad. |
| Class | UnrecognizedBugTrackerURL | The given URL isn't used by any bug tracker we support. |
| Interface | IBugWatchActivity | A record of a single BugWatch update. |
| Class | BugWatchCannotBeRescheduled | The current IBugWatch can't be rescheduled. |