minor fix to Actor.flush() with controlJoints

panda/src/chan/animChannelMatrixDynamic.cxx

@@ -38,7 +38,9 @@ AnimChannelMatrixDynamic::
 AnimChannelMatrixDynamic(AnimGroup *parent, const string &name)
   : AnimChannelMatrix(parent, name) 
 {
-  _last_value = _value = TransformState::make_identity();
+  _value = TransformState::make_identity();
+  _last_value = NULL;  // This is impossible; thus, has_changed() will
+                       // always return true the first time.
 }
 
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