Clear reference locals before calling

[Roldak]

begin{
    def f(b: bool) => {
        if (b) {
            let x = new Int(2)
        }
        else{
            Thread.forcecollection()
        }
    }

    f(true)
    Thread.forcecollection()
    f(false)
}

[Roldak]

should be ok now