teaching languages: fix copying of `test~object' binding to REPL
teaching languages: fix copying of `test~object' binding to REPL

As Mike noticed, commit d836cba7c9 triggered a different binding
of `test~object' due to the enclosing module context of the `eval'ed
syntax object.

mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket