Make test harness and comments match Kubernetes behaviour on conflict error

Kubernetes always returns nil on error; somehow I had the wrong idea
here.

prog/kube-utils/annotations.go

@@ -100,7 +100,7 @@ func (cml *configMapAnnotations) UpdateAnnotation(key, value string) (err error)
 		return errors.New("endpoint not initialized, call Init first")
 	}
 	// speculatively change the state, then replace with whatever comes back
-	// from Update(), which will be the latest on the server whatever happened
+	// from Update(), which will be the latest on the server, or nil if error
 	cml.cm.Annotations[cleanKey(key)] = value
 	cml.cm, err = cml.Client.ConfigMaps(cml.Namespace).Update(cml.cm)
 	return err
@@ -111,7 +111,7 @@ func (cml *configMapAnnotations) RemoveAnnotation(key string) (err error) {
 		return errors.New("endpoint not initialized, call Init first")
 	}
 	// speculatively change the state, then replace with whatever comes back
-	// from Update(), which will be the latest on the server whatever happened
+	// from Update(), which will be the latest on the server, or nil if error
 	delete(cml.cm.Annotations, cleanKey(key))
 	cml.cm, err = cml.Client.ConfigMaps(cml.Namespace).Update(cml.cm)
 	return err
@@ -122,7 +122,7 @@ func (cml *configMapAnnotations) RemoveAnnotationsWithValue(valueToRemove string
 		return errors.New("endpoint not initialized, call Init first")
 	}
 	// speculatively change the state, then replace with whatever comes back
-	// from Update(), which will be the latest on the server whatever happened
+	// from Update(), which will be the latest on the server, or nil if error
 	for key, value := range cml.cm.Annotations {
 		if value == valueToRemove {
 			delete(cml.cm.Annotations, key) // don't need to clean this key as it came from the map

testing/kubernetes/testing/fixture.go

@@ -110,10 +110,6 @@ func ObjectReaction(tracker ObjectTracker) testing.ReactionFunc {
 			}
 			err = tracker.Update(gvr, action.GetObject(), ns)
 			if err != nil {
-				if errors.IsConflict(err) { // return the currently-stored version of the object
-					obj, _ := tracker.Get(gvr, ns, objMeta.GetName())
-					return true, obj, err
-				}
 				return true, nil, err
 			}
 			obj, err := tracker.Get(gvr, ns, objMeta.GetName())