change list sessions stop signal to upcoming new-sm git master. This will break the program for now if you don't compiled nsm from source!

engine/nsmservercontrol.py

@@ -649,12 +649,16 @@ class NsmServerControl(object):
                     self._queue.append(msg)
                     continue
                 #This is what we want:
-                elif msg.oscpath == "/reply" and msg.params[0] == "/nsm/server/list":
-                    #/reply ['/nsm/server/list', 'test3']
-                    self.internalState["sessions"].add(msg.params[1])
-                    logger.info(f"Received session name: {msg.params[1]}")
-                elif msg.params[0] == 0 and msg.params[1] == "Done.":
-                    break
+                elif msg.oscpath == "/reply" and msg.params[0] == "/nsm/server/list":                    
+                    #/reply ['/nsm/server/list', 'test3']  for a real session or
+                    #/reply ['/nsm/server/list', ''] as "list ended" marker
+                    if msg.params[1]:
+                        self.internalState["sessions"].add(msg.params[1])
+                        logger.info(f"Received session name: {msg.params[1]}")
+                    else: #empty string
+                        break
+                #elif msg.params[0] == 0 and msg.params[1] == "Done.": # legacy nsmd sent the wrong message. Fixed in new-session-manager june 2020
+                #    break
                 else:
                     logger.warning(f"Expected project but got path {msg.oscpath} with {msg.params}. Adding to queue for later.")
                     self._queue.append(msg)