pool: update client subscription state before responding.

This fixes a bug where the subscription state would be out
of sync with the client because the response was getting sent
before the state was updated.

Author: dnldd

pool/client.go

@@ -333,11 +333,12 @@ func (c *Client) handleSubscribeRequest(req *Request, allowed bool) error {
 		resp = SubscribeResponse(*req.ID, nid, c.extraNonce1, ExtraNonce2Size, nil)
 	}
 
-	c.ch <- resp
 	c.subscribedMtx.Lock()
 	c.subscribed = true
 	c.subscribedMtx.Unlock()
 
+	c.ch <- resp
+
 	return nil
 }