rpcClient should attempt a reconnect if the call fails
with 'rpc.ErrShutdown' this is needed since at times when
the servers are taken down and brought back up.
The hijacked connection from net.Dial is usually closed.
So upon first attempt rpcClient might falsely indicate that
disk to be down, to avoid this state make another dial attempt
to really fail.
Fixes#3206Fixes#3205
Harshavardhana