On 04/21/2014 07:43 AM, Stefan Monnier wrote:
>> +        (condition-case err
>> +            (vc-call-backend backend 'root default-directory)
>> +          (vc-not-supported
>> +           (unless (eq (cadr err) 'root)
>> +             (signal (car err) (cdr err)))
>> +           nil)))))
> 
> Why do we need this gymnastics?

So that we don't accidentally suppress errors we *don't* expect to get.