match: Don't ever avoid let-binding the matched expression (since identifiers can have non-trivial effects).  Bug pointed out by RMC.
match: Don't ever avoid let-binding the matched expression (since
identifiers can have non-trivial effects).  Bug pointed out by RMC.

svn: r3813

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