Replace special variable in test for unbound slot by call to predicate function.
Replace special variable in test for unbound slot by call to predicate function.

vtomole/SICL,clasp-developers/SICL,clasp-developers/SICL,vtomole/SICL,vtomole/SICL,clasp-developers/SICL,clasp-developers/SICL,vtomole/SICL