git-codereview: specify --no-track on checkout

My global git config contains

```
[branch]
  autosetupmerge = always
```

As a result, git checkout creates a tracking branch,
so the current branch is master instead of origin/master.
Override the config by specifying --no-track.

Fixes golang/go#9379

Change-Id: I00e0f756606f2b7cb2354cb26e8e58eb7cd33274
Reviewed-on: https://go-review.googlesource.com/23969
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>
1 file changed