Update go dependencies

vendor/google.golang.org/appengine/internal/api_common.go

@@ -5,10 +5,15 @@
 package internal
 
 import (
+	"errors"
+	"os"
+
 	"github.com/golang/protobuf/proto"
 	netcontext "golang.org/x/net/context"
 )
 
+var errNotAppEngineContext = errors.New("not an App Engine context")
+
 type CallOverrideFunc func(ctx netcontext.Context, service, method string, in, out proto.Message) error
 
 var callOverrideKey = "holds []CallOverrideFunc"
@@ -77,10 +82,42 @@ func Logf(ctx netcontext.Context, level int64, format string, args ...interface{
 		f(level, format, args...)
 		return
 	}
-	logf(fromContext(ctx), level, format, args...)
+	c := fromContext(ctx)
+	if c == nil {
+		panic(errNotAppEngineContext)
+	}
+	logf(c, level, format, args...)
 }
 
 // NamespacedContext wraps a Context to support namespaces.
 func NamespacedContext(ctx netcontext.Context, namespace string) netcontext.Context {
 	return withNamespace(ctx, namespace)
 }
+
+// SetTestEnv sets the env variables for testing background ticket in Flex.
+func SetTestEnv() func() {
+	var environ = []struct {
+		key, value string
+	}{
+		{"GAE_LONG_APP_ID", "my-app-id"},
+		{"GAE_MINOR_VERSION", "067924799508853122"},
+		{"GAE_MODULE_INSTANCE", "0"},
+		{"GAE_MODULE_NAME", "default"},
+		{"GAE_MODULE_VERSION", "20150612t184001"},
+	}
+
+	for _, v := range environ {
+		old := os.Getenv(v.key)
+		os.Setenv(v.key, v.value)
+		v.value = old
+	}
+	return func() { // Restore old environment after the test completes.
+		for _, v := range environ {
+			if v.value == "" {
+				os.Unsetenv(v.key)
+				continue
+			}
+			os.Setenv(v.key, v.value)
+		}
+	}
+}