Override the ExtractExtensions function.

It turns out that identity changes the response body structure.
diff --git a/openstack/identity/v2/extensions/delegate_test.go b/openstack/identity/v2/extensions/delegate_test.go
index 5cc7c12..90eb21b 100644
--- a/openstack/identity/v2/extensions/delegate_test.go
+++ b/openstack/identity/v2/extensions/delegate_test.go
@@ -26,7 +26,7 @@
 	th.SetupHTTP()
 	defer th.TeardownHTTP()
 
-	th.Mux.HandleFunc("/v2.0/extensions", func(w http.ResponseWriter, r *http.Request) {
+	th.Mux.HandleFunc("/extensions", func(w http.ResponseWriter, r *http.Request) {
 		th.TestMethod(t, r, "GET")
 		th.TestHeader(t, r, "X-Auth-Token", TokenID)
 
@@ -34,28 +34,28 @@
 
 		fmt.Fprintf(w, `
 {
-    "extensions": [
-        {
-            "updated": "2013-01-20T00:00:00-00:00",
-            "name": "Neutron Service Type Management",
-            "links": [],
-            "namespace": "http://docs.openstack.org/ext/neutron/service-type/api/v1.0",
-            "alias": "service-type",
-            "description": "API for retrieving service providers for Neutron advanced services"
-        }
-    ]
+	"extensions": {
+		"values": [
+			{
+				"updated": "2013-01-20T00:00:00-00:00",
+				"name": "Neutron Service Type Management",
+				"links": [],
+				"namespace": "http://docs.openstack.org/ext/neutron/service-type/api/v1.0",
+				"alias": "service-type",
+				"description": "API for retrieving service providers for Neutron advanced services"
+			}
+		]
+	}
 }
-      `)
+		`)
 	})
 
 	count := 0
 
-	List(ServiceClient()).EachPage(func(page pagination.Page) (bool, error) {
+	err := List(ServiceClient()).EachPage(func(page pagination.Page) (bool, error) {
 		count++
 		actual, err := ExtractExtensions(page)
-		if err != nil {
-			t.Errorf("Failed to extract extensions: %v", err)
-		}
+		th.AssertNoErr(t, err)
 
 		expected := []Extension{
 			Extension{
@@ -74,17 +74,15 @@
 
 		return true, nil
 	})
-
-	if count != 1 {
-		t.Errorf("Expected 1 page, got %d", count)
-	}
+	th.AssertNoErr(t, err)
+	th.CheckEquals(t, 1, count)
 }
 
 func TestGet(t *testing.T) {
 	th.SetupHTTP()
 	defer th.TeardownHTTP()
 
-	th.Mux.HandleFunc("/v2.0/extensions/agent", func(w http.ResponseWriter, r *http.Request) {
+	th.Mux.HandleFunc("/extensions/agent", func(w http.ResponseWriter, r *http.Request) {
 		th.TestMethod(t, r, "GET")
 		th.TestHeader(t, r, "X-Auth-Token", TokenID)