Fixed #27685 -- Added watchman support to the autoreloader.

Removed support for pyinotify (refs #9722).

django/apps/registry.py

@@ -42,6 +42,8 @@ class Apps:
 
         # Whether the registry is populated.
         self.apps_ready = self.models_ready = self.ready = False
+        # For the autoreloader.
+        self.ready_event = threading.Event()
 
         # Lock for thread-safe population.
         self._lock = threading.RLock()
@@ -120,6 +122,7 @@ class Apps:
                 app_config.ready()
 
             self.ready = True
+            self.ready_event.set()
 
     def check_apps_ready(self):
         """Raise an exception if all apps haven't been imported yet."""