[sheepdog] master_idx question

[Dietmar Maurer]

> Master is internal concept known by the code, which is used to manage the
> node join (check if it is allowed in).
> 
> Master transfer only happens when we try to boot up a previously crashed
> cluster which might has different epoch, so mastership is transferred to
> highest epoch node.
> 
> For admins, he isn't supposed to know which is the master.

I consider myself as developer, and I want to know the master id if there is a master.
Why don't you simple set master_idx (if there is a master)?