[short] skip 'builds go programs'

go build -o cacheprog$GOEXE cacheprog.go
env GOCACHEPROG=$GOPATH/src/cacheprog$GOEXE

# This should not deadlock
go build simple.go
! stderr 'cacheprog closed'

-- simple.go --
package main

func main() {}
-- cacheprog.go --
// This is a minimal GOCACHEPROG program that doesn't respond to close.
package main

import (
    "encoding/json"
    "os"
)

func main() {
    json.NewEncoder(os.Stdout).Encode(map[string][]string{"KnownCommands": {"close"}})
    var res struct{}
    json.NewDecoder(os.Stdin).Decode(&res)
}