applying patch by rxtsolar: https://github.com/Itseez/opencv/pull/5422 for the master branch (even though it's actually not that important here)

modules/ml/src/svm.cpp

@@ -1822,8 +1822,8 @@ public:
             }
         }
 
-        params = best_params;
         class_labels = class_labels0;
+        setParams(best_params);
         return do_train( samples, responses );
     }