Functional impact:
With new Redis scale-out from dev branch, on server calling the method Groups.Add(connectionId, groupName).Wait() never completes, on the client method (which invokes that server’s method), either the .done callback or the .fail callback will not get executed, this repro on all transports.
In this case it also causes the webSockets transport client to no longer be able to send messages, but it can still receive messages.

Note, this is regression from 2.1.1

Repro steps:
1). Use AspNet SignalR sample, update it to use Redis scale-out
2). Browse to Hubs/HubConnectionAPI/Default.aspx page, use webSockets transport
3). Input "group1" in "Group" textbox, Click button "Join Group"
it will call below Hub method:

        public string JoinGroup(string connectionId, string groupName)
        {
            Groups.Add(connectionId, groupName).Wait();
            return connectionId + " joined " + groupName;
        }

4). Click button "Broadcast".

Expected result:
Page shows "Succeeded at joinGroup: group1" or shows "Failed at joinGroup: group1".
Page shows the message "Clients.All ......" for broadcast click.

Actual result:
Groups.Add(connectionId, groupName).Wait() never completes.
The server doesn't receive messages from the client.
The page doesn't show the expected messages.