Fix panic in findBuffers when Any pattern is used

memstore.go

@@ -375,7 +375,7 @@ func (m *MemoryStore) Read(selector Selector, metric string, from, to int64) ([]
 	if err != nil {
 		return nil, 0, 0, err
 	} else if n == 0 {
-		return nil, 0, 0, errors.New("metric not found")
+		return nil, 0, 0, errors.New("metric or host not found")
 	} else if n > 1 {
 		if minfo.aggregation == AvgAggregation {
 			normalize := 1. / Float(n)

selector.go

@@ -111,6 +111,7 @@ func (l *level) findBuffers(selector Selector, offset int, f func(b *buffer) err
 				return err
 			}
 		}
+		return nil
 	}
 
 	panic("impossible")