Enhance the producer-brief enhancement
Enhance the producer-brief enhancement

1. If producer is a number larger than 0 then look up the value in
   producer-raw-to-producer
2. If producer is nil or a number equal to 0 then construct the
   producer-brief from producer-long and producer-place (if either of
   them is not nil)

Apparently the library system contains quite a few records where the
producer is nil, so this should cover up those cases.

sbsdev/catalog