8352185: Shenandoah: Invalid logic for remembered set verification

src/hotspot/share/gc/shenandoah/shenandoahOldGeneration.cpp

@@ -792,6 +792,7 @@ void ShenandoahOldGeneration::complete_mixed_evacuations() {
   }
 
   if (state() == ShenandoahOldGeneration::EVACUATING) {
+    set_parsable(false);
     transition_to(ShenandoahOldGeneration::FILLING);
     return;
   }