impl/memory: Disallow empty namespace.

impl/dummy/dummy.go

Index: impl/dummy/dummy.go
diff --git a/impl/dummy/dummy.go b/impl/dummy/dummy.go
index dd323cd75c3856563d31577ced0e2ac641596730..43ecbe50c49b8225a33db99b5469becb63b39fe4 100644
--- a/impl/dummy/dummy.go
+++ b/impl/dummy/dummy.go
@@ -144,7 +144,7 @@ type i struct{}
 func (i) AccessToken(scopes ...string) (token string, expiry time.Time, err error) { panic(ni()) }
 func (i) AppID() string                                                            { return "appid" }
 func (i) FullyQualifiedAppID() string                                              { return "dummy~appid" }
-func (i) GetNamespace() string                                                     { return "dummy-namespace" }
+func (i) GetNamespace() (string, bool)                                             { return "dummy-namespace", true }
 func (i) ModuleHostname(module, version, instance string) (string, error)          { panic(ni()) }
 func (i) ModuleName() string                                                       { panic(ni()) }
 func (i) DefaultVersionHostname() string                                           { panic(ni()) }