[1.10.x] Fixed #25044 -- Fixed migrations for renaming ManyToManyField's through model.

Backport of f1e408ff40d2c1753f92515c70a44634b4d47467 from master

2 files changed, 29 insertions, 0 deletions

diff --git a/django/db/migrations/autodetector.py b/django/db/migrations/autodetector.py
index 08baf473b0..ae88a90465 100644
--- a/django/db/migrations/autodetector.py
+++ b/django/db/migrations/autodetector.py
@@ -867,6 +867,13 @@ class MigrationAutodetector(object):
                 )
                 if rename_key in self.renamed_models:
                     new_field.remote_field.model = old_field.remote_field.model
+            if hasattr(new_field, "remote_field") and getattr(new_field.remote_field, "through", None):
+                rename_key = (
+                    new_field.remote_field.through._meta.app_label,
+                    new_field.remote_field.through._meta.model_name,
+                )
+                if rename_key in self.renamed_models:
+                    new_field.remote_field.through = old_field.remote_field.through
             old_field_dec = self.deep_deconstruct(old_field)
             new_field_dec = self.deep_deconstruct(new_field)
             if old_field_dec != new_field_dec:
diff --git a/django/db/migrations/operations/models.py b/django/db/migrations/operations/models.py
index 10af84cc47..d18fded97c 100644
--- a/django/db/migrations/operations/models.py
+++ b/django/db/migrations/operations/models.py
@@ -307,6 +307,28 @@ class RenameModel(ModelOperation):
                 new_fields.append((name, field))
             state.models[related_key].fields = new_fields
             state.reload_model(*related_key)
+        # Repoint M2Ms with through pointing to us
+        related_models = {
+            f.remote_field.model for f in model._meta.fields
+            if getattr(f.remote_field, 'model', None)
+        }
+        model_name = '%s.%s' % (app_label, self.old_name)
+        for related_model in related_models:
+            if related_model == model:
+                related_key = (app_label, self.new_name_lower)
+            else:
+                related_key = (related_model._meta.app_label, related_model._meta.model_name)
+            new_fields = []
+            changed = False
+            for name, field in state.models[related_key].fields:
+                if field.is_relation and field.many_to_many and field.remote_field.through == model_name:
+                    field = field.clone()
+                    field.remote_field.through = '%s.%s' % (app_label, self.new_name)
+                    changed = True
+                new_fields.append((name, field))
+            if changed:
+                state.models[related_key].fields = new_fields
+                state.reload_model(*related_key)
         state.reload_model(app_label, self.new_name_lower)
 
     def database_forwards(self, app_label, schema_editor, from_state, to_state):