Grind doesn't see assignments in select cases

[dgryski]

Here is a trimmed down test case:

package main

import "fmt"

func main() {

    ch := make(chan int)

    var ok bool
    var m int
    select {
    case m, ok = <-ch:
        if ok {
            fmt.Println(m)
        }
    }
}

after grinding becomes

package main

import "fmt"

func main() {
    ch := make(chan int)

    select {
    case m, ok = <-ch:
        var ok bool
        if ok {
            var m int
            fmt.Println(m)
        }
    }
}

which fails to build because the declarations of m and ok now appear after their first use in the select case.