[autotest] Handle invalid restricted group name.

On the servers where the restricted groups is set
to something like "USE SHADOW CONFIG", is_restricted_user
will fail with a key error because "USE SHADOW CONFIG"
is not a valid group.

This CL handle the error properly.

TEST=None
BUG=None

Change-Id: I61a310c976488c47a51ff99855a0aea6bffc7b92
Reviewed-on: https://chromium-review.googlesource.com/327062
Reviewed-by: Don Garrett <dgarrett@chromium.org>
Tested-by: Fang Deng <fdeng@chromium.org>
Reviewed-by: Paul Hobbs <phobbs@google.com>
Commit-Queue: Fang Deng <fdeng@chromium.org>
1 file changed