cannot debug this particular example

Nobody has claimed this yet.

``` go
package main

import (
"fmt"
"time"
"math/rand"
)

func f(n int) {
for i := 0; i < 10; i++ {
fmt.Println(n, ":", i)
amt := time.Duration(rand.Intn(250))
_ = "breakpoint"
time.Sleep(time.Millisecond * amt)
}
}

func main() {
for i := 0; i < 10; i++ {
go f(i)
}
var input string
fmt.Scanln(&input)
}
```

Running:

```
c:\Go\EXTERNAL\bin\godebug.exe run simgoroutines.go
```

And output:

```
0 : 0
1 : 0
5 : 0
4 : 0
7 : 0
2 : 0
3 : 0
8 : 0
6 : 0
9 : 0
-> _ = "breakpoint"
(godebug) 8 : 1
4 : 1
9 : 1
4 : 2
2 : 1
7 : 1
5 : 1
[...]
```

The program then exits when I try to issue any of the commands from godebug (h, e.g.). Any way to override the reading from stdin?

Reproduce the failure with the supplied Go goroutine example using `godebug.exe run simgoroutines.go`, then trace how debugger commands and the target program's stdin are handled. Done means the target can call `fmt.Scanln` without causing debugger commands such as `h` to exit the session.

Written by the indexing model from the issue text.