Stop failing for old-style main in codeworld mode.
Stop failing for old-style main in codeworld mode.

Fixes #752

google/codeworld,alphalambda/codeworld,pranjaltale16/codeworld,google/codeworld,alphalambda/codeworld,google/codeworld,pranjaltale16/codeworld,alphalambda/codeworld,pranjaltale16/codeworld