Added test for FOR-THE-HASH-KEYS-OF USING NIL variable.
Added test for FOR-THE-HASH-KEYS-OF USING NIL variable.

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