when turning mpi off, don't broadcast if mpi was never enabled

phoebe/__init__.py

@@ -162,7 +162,7 @@ def on(self, nprocs=None):
             self.nprocs = nprocs
 
     def off(self):
-        if self.within_mpirun and self.myrank == 0:
+        if self.within_mpirun and self.enabled and self.myrank == 0:
             self.comm.bcast({'worker_command': 'release'}, root=0)
 
         self._enabled = False