[developers] Trying to operate on background stream : [incr tsdb()] affected as well

[Ann Copestake]

crysmann at dfki.de said:
> I've tried out finish-output instead of force-output, but to no avail.  Error
> is the same...

OK, thanks, it's presumably something to do with the nature of that stream - 
possibly these are the only places it's called on an interactive stream.
Commenting out remains the official workaround, but I won't check in that 
version since we haven't got the patch in by default yet