macro-introduced variables clobber the top-level

[Abdulaziz Ghuloum]

> (define-syntax def
    (syntax-rules ()
      [(_ name val)
       (begin
         (define tmp val) ;;; this should be fresh
         (define (name) tmp))]))
> (def x 12)
> (x)
12
> (def y 13)
> (y)
13
> (x)
13 ;;; should be 12
> tmp
13 ;;; should not be visible

[Abdulaziz Ghuloum (aghuloum)]

Fixed in rev 1459.