Fixed #13335: Adjusted the r12950 fix to properly handle import errors resulting from nested calls to load_app.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@12972 bcc190cf-cafb-0310-a4f2-bffc1f526a37

tests/regressiontests/admin_scripts/complex_app/models/foo.py

@@ -0,0 +1,6 @@
+from django.db import models
+
+class Foo(models.Model):
+    name = models.CharField(max_length=5)
+    class Meta:
+        app_label = 'complex_app'