Fixed #26304 -- Ignored unmanaged through model in table introspection.

AUTHORS

@@ -481,6 +481,7 @@ answer newbie questions, and generally made Django that much better:
     Matt Deacalion Stevens <matt@dirtymonkey.co.uk>
     Matt Dennenbaum
     Matthew Flanagan <http://wadofstuff.blogspot.com>
+    Matthew Schinckel <matt@schinckel.net>
     Matthew Somerville <matthew-django@dracos.co.uk>
     Matthew Tretter <m@tthewwithanm.com>
     Matthias Kestenholz <mk@406.ch>

django/db/backends/base/introspection.py

@@ -80,7 +80,10 @@ class BaseDatabaseIntrospection(object):
                 if not model._meta.managed:
                     continue
                 tables.add(model._meta.db_table)
-                tables.update(f.m2m_db_table() for f in model._meta.local_many_to_many)
+                tables.update(
+                    f.m2m_db_table() for f in model._meta.local_many_to_many
+                    if f.remote_field.through._meta.managed
+                )
         tables = list(tables)
         if only_existing:
             existing_tables = self.table_names(include_views=include_views)

tests/introspection/models.py

@@ -45,6 +45,7 @@ class Article(models.Model):
     body = models.TextField(default='')
     reporter = models.ForeignKey(Reporter, models.CASCADE)
     response_to = models.ForeignKey('self', models.SET_NULL, null=True)
+    unmanaged_reporters = models.ManyToManyField(Reporter, through='ArticleReporter')
 
     def __str__(self):
         return self.headline
@@ -54,3 +55,11 @@ class Article(models.Model):
         index_together = [
             ["headline", "pub_date"],
         ]
+
+
+class ArticleReporter(models.Model):
+    article = models.ForeignKey(Article, models.CASCADE)
+    reporter = models.ForeignKey(Reporter, models.CASCADE)
+
+    class Meta:
+        managed = False

tests/introspection/tests.py

@@ -6,7 +6,7 @@ from django.db import connection
 from django.db.utils import DatabaseError
 from django.test import TransactionTestCase, mock, skipUnlessDBFeature
 
-from .models import Article, City, Reporter
+from .models import Article, ArticleReporter, City, Reporter
 
 
 class IntrospectionTests(TransactionTestCase):
@@ -53,6 +53,10 @@ class IntrospectionTests(TransactionTestCase):
         self.assertNotIn('introspection_article_view',
                          connection.introspection.table_names())
 
+    def test_unmanaged_through_model(self):
+        tables = connection.introspection.django_table_names()
+        self.assertNotIn(ArticleReporter._meta.db_table, tables)
+
     def test_installed_models(self):
         tables = [Article._meta.db_table, Reporter._meta.db_table]
         models = connection.introspection.installed_models(tables)