Use a vendor directory for repeatable builds - fixes #816

This is using godep to manage the vendor directory.

vendor/google.golang.org/appengine/namespace.go

@@ -0,0 +1,48 @@
+// Copyright 2012 Google Inc. All rights reserved.
+// Use of this source code is governed by the Apache 2.0
+// license that can be found in the LICENSE file.
+
+package appengine
+
+import (
+	"fmt"
+	"regexp"
+
+	"github.com/golang/protobuf/proto"
+
+	"google.golang.org/appengine/internal"
+	basepb "google.golang.org/appengine/internal/base"
+)
+
+// Namespace returns a replacement context that operates within the given namespace.
+func Namespace(c Context, namespace string) (Context, error) {
+	if !validNamespace.MatchString(namespace) {
+		return nil, fmt.Errorf("appengine: namespace %q does not match /%s/", namespace, validNamespace)
+	}
+	return &namespacedContext{
+		Context:   c,
+		namespace: namespace,
+	}, nil
+}
+
+// validNamespace matches valid namespace names.
+var validNamespace = regexp.MustCompile(`^[0-9A-Za-z._-]{0,100}$`)
+
+// namespacedContext wraps a Context to support namespaces.
+type namespacedContext struct {
+	Context
+	namespace string
+}
+
+func (n *namespacedContext) Call(service, method string, in, out proto.Message, opts *internal.CallOptions) error {
+	// Apply any namespace mods.
+	if mod, ok := internal.NamespaceMods[service]; ok {
+		mod(in, n.namespace)
+	}
+	if service == "__go__" && method == "GetNamespace" {
+		out.(*basepb.StringProto).Value = proto.String(n.namespace)
+		return nil
+	}
+
+	return n.Context.Call(service, method, in, out, opts)
+}