[1.10.x] Fixed #26778 -- Fixed ModelSignal.connect() weak argument.

Backport of 9bf8d50a67 from master

django/db/models/signals.py

@@ -27,7 +27,10 @@ class ModelSignal(Signal):
             return partial_method(sender)
 
     def connect(self, receiver, sender=None, weak=True, dispatch_uid=None, apps=None):
-        self._lazy_method(super(ModelSignal, self).connect, apps, receiver, sender, dispatch_uid=dispatch_uid)
+        self._lazy_method(
+            super(ModelSignal, self).connect, apps, receiver, sender,
+            weak=weak, dispatch_uid=dispatch_uid,
+        )
 
     def disconnect(self, receiver=None, sender=None, weak=None, dispatch_uid=None, apps=None):
         if weak is not None:

tests/signals/tests.py

@@ -4,7 +4,7 @@ from django.apps.registry import Apps
 from django.db import models
 from django.db.models import signals
 from django.dispatch import receiver
-from django.test import TestCase
+from django.test import TestCase, mock
 from django.test.utils import isolate_apps
 from django.utils import six
 
@@ -258,6 +258,19 @@ class SignalTests(BaseSignalTest):
         self.assertTrue(b._run)
         self.assertEqual(signals.post_save.receivers, [])
 
+    @mock.patch('weakref.ref')
+    def test_lazy_model_signal(self, ref):
+        def callback(sender, args, **kwargs):
+            pass
+        signals.pre_init.connect(callback)
+        signals.pre_init.disconnect(callback)
+        self.assertTrue(ref.called)
+        ref.reset_mock()
+
+        signals.pre_init.connect(callback, weak=False)
+        signals.pre_init.disconnect(callback)
+        ref.assert_not_called()
+
 
 class LazyModelRefTest(BaseSignalTest):
     def setUp(self):