Fixed #28984 -- Made assorted code simplifications.

django/dispatch/dispatcher.py

@@ -215,12 +215,10 @@ class Signal:
         # Note: caller is assumed to hold self.lock.
         if self._dead_receivers:
             self._dead_receivers = False
-            new_receivers = []
-            for r in self.receivers:
-                if isinstance(r[1], weakref.ReferenceType) and r[1]() is None:
-                    continue
-                new_receivers.append(r)
-            self.receivers = new_receivers
+            self.receivers = [
+                r for r in self.receivers
+                if not(isinstance(r[1], weakref.ReferenceType) and r[1]() is None)
+            ]
 
     def _live_receivers(self, sender):
         """