BUG FIX: correct slot indexing scheme in the hash table lookup.
BUG FIX: correct slot indexing scheme in the hash table lookup.

We were looking up a slot index in the range [0,nslots-1] whereas the
array was in the range [1,nslots].  Oops...

Fixed by simply adding 1 to the value returned by the modulo of the hash
of the label.

Reported by: Nick Blunt.

hande-qmc/hande,hande-qmc/hande,hande-qmc/hande,hande-qmc/hande,ruthfranklin/hande,hande-qmc/hande