Fail properly when Base URL Resolution fails
Created by: davemevans
Debugging #1701 showed a bug that has always existed but was only exposed once the fast switch changes were added.
If URL resolution fails, an event is fired which stops the scheduler. If you subsequently try to resolve a Base URL after this (which in theory should never happen, but can in certain circumstances), the resolver can return unexpected results. This change ensures that no sensible result is returned once a failure has occurred.
This is a one line change (L91, BaseURLController) - all the other stuff is simply to get the test running to verify the fix.