IsDisconnected not working on real server disconnect

[jwang-r7]

IsDisconnected works when calling conn.Close(). However, when killing the server it's connected to in a real scenario doesn't seem to return the same.

I have seen it return:

• ErrConnClosed
• Named pipe file closed from the library that I'm using

Not sure if it will return ExcClosed at any point.

f, release = myclient.MyMethod(ctx, func(ps rpc_api.Params) error {
		// Some CB
               return nil
	})
val, err := f.Struct() // catching connection err

[zenhack]

I will hazard a guess that we have code that is handling message send failures by just propagating the error returned by the transport; probably to fix this we need to update those call sites to wrap the error.