[1.5.x] Fixed #19806 -- Ensure that content types and permissions aren't created for swapped models.

Thanks to rizumu for the report.

Backport of c8985a8a73.

tests/regressiontests/swappable_models/models.py

@@ -0,0 +1,15 @@
+from django.db import models
+
+
+class Article(models.Model):
+    title =  models.CharField(max_length=100)
+    publication_date = models.DateField()
+
+    class Meta:
+        swappable = 'TEST_ARTICLE_MODEL'
+
+
+class AlternateArticle(models.Model):
+    title =  models.CharField(max_length=100)
+    publication_date = models.DateField()
+    byline = models.CharField(max_length=100)