did not work, fixed

Author: menghanl

Diff for: proxy.go

@@ -91,7 +91,7 @@ func doHTTPConnectHandshake(ctx context.Context, conn net.Conn, backendAddr stri
 	if t := proxyURL.User; t != nil {
 		u := t.Username()
 		p, _ := t.Password()
-		req.Header.Add(proxyAuthHeaderKey, basicAuth(u, p))
+		req.Header.Add(proxyAuthHeaderKey, "Basic "+basicAuth(u, p))
 	}
 
 	if err := sendHTTPRequest(ctx, req, conn); err != nil {

Diff for: proxy_test.go

@@ -199,7 +199,7 @@ func TestHTTPConnectBasicAuth(t *testing.T) {
 			if req.UserAgent() != grpcUA {
 				return fmt.Errorf("unexpect user agent %q, want %q", req.UserAgent(), grpcUA)
 			}
-			wantProxyAuthStr := base64.StdEncoding.EncodeToString([]byte(user + ":" + password))
+			wantProxyAuthStr := "Basic " + base64.StdEncoding.EncodeToString([]byte(user+":"+password))
 			if got := req.Header.Get(proxyAuthHeaderKey); got != wantProxyAuthStr {
 				gotDecoded, _ := base64.StdEncoding.DecodeString(got)
 				wantDecoded, _ := base64.StdEncoding.DecodeString(wantProxyAuthStr)