[plt-scheme] call-with-continuation-barrier and multiple values

call/barrier fails miserably if the thunk returns multiple values:

> (version)
"4.1.2.4"
; svn from a couple of days ago
> (call-with-continuation-barrier (lambda () (values 1 2 3)))
context expected 1 value, received 3 values: 1 2 3
>

-- vyzo