fix partial chain (#596)

src/KubernetesClient/Kubernetes.ConfigInit.cs

@@ -65,9 +65,9 @@ namespace k8s
         {
             Initialize();
             ValidateConfig(config);
-            CreateHttpClient(handlers, config);
             CaCerts = config.SslCaCerts;
             SkipTlsVerify = config.SkipTlsVerify;
+            CreateHttpClient(handlers, config);
             InitializeFromConfig(config);
         }
 
@@ -216,6 +216,11 @@ namespace k8s
                     return new NetworkStream(socket, ownsSocket: true);
                 };
 
+
+                // set HttpClientHandler's cert callback before replace _underlyingHandler
+                // force HttpClientHandler use our callback
+                InitializeFromConfig(config);
+
                 var p = HttpClientHandler.GetType().GetField("_underlyingHandler", BindingFlags.NonPublic | BindingFlags.Instance);
                 p.SetValue(HttpClientHandler, (sh));
             }