use tail recursion, not because of speed, but because breaking code would always have bad context dumps
use tail recursion, not because of speed, but because breaking code would always have bad context dumps

svn: r17427

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