CRM_Core_Error::fatal triggering non-descriptive php exceptions in some cases

CRM_Core_Error::fatal seems to have been changed recently to trigger a non-descriptive php exception in some cases in place of the error it was asked to produce.

When making a change of this nature to such an important and widely-called function, some comments explaining the change would be really helpful.

As far as I can tell, this seems to have been put here so that errors in jobs run through the job api can be caught, causing the system to move onto the next job without halting execution, but it's pretty unclear what this change is meant to achieve.

If we must do this, could we at least append the actual error message to the php exception, rather than throwing it away and replacing it with 'A fatal error was triggered'? or it makes problems very difficult to debug.

A patch to do this is attached.