Ensure that awc::ws::WebsocketsRequest sets the Host header before connecting.

awc/src/ws.rs

@@ -233,6 +233,8 @@ impl WebsocketsRequest {
             return Either::A(err(InvalidUrl::UnknownScheme.into()));
         }
 
+        self.head.headers.insert(header::HOST, HeaderValue::from_str(uri.host().unwrap()).unwrap());
+
         // set cookies
         if let Some(ref mut jar) = self.cookies {
             let mut cookie = String::new();