Process warning messages after calling integrator_synchronize from py…

…thon.

rebound/simulation.py

@@ -1417,6 +1417,7 @@ def integrator_synchronize(self):
         Call this function if safe-mode is disabled and you need to synchronize particle positions and velocities between timesteps.
         """
         clibrebound.reb_simulation_synchronize(byref(self))
+        self.process_messages()
 
     def tree_update(self):
         """