Closures and channel operations result in a bug

The following doesn't produce the expected output:

```go
package main

var strch = make(chan string)

func main() {
	strch := strch // comment this line to avoid the bug
	go func() {
		println("sending...")
		strch <- "hello"
		println("sent!")
	}()
	println(<-strch)
}
```

There appears to be some sort of interaction between closures and channel operations that goes wrong.