i.e. If I have done:

```
$ repo init -b froyo; repo sync

```

and I come back to this repo later, how can I determine which the version checked out is?
In other words, the response to:

```
$ "unknown command which I am looking for"

```

should be "froyo" in this case (or the respective version number), 
after:

```
$ repo init -b gingerbread; repo sync

```

it should be "gingerbread" (or the respective version number)