Prefetch related does not work for fkey to multitable inherited model

[milosu]

Using Django 1.4 with some latest prefetch related patches from trunk, the prefetch_related does not work for fkeys to models that are inherited from some other model.

Without the applied patch, the attached test case fails with:

======================================================================
ERROR: test_foreignkey (modeltests.prefetch_related.tests.MultiTableInheritanceT
est)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "C:\Python26\Lib\site-packages\django_versions\trunk\tests\modeltests\pre
fetch_related\tests.py", line 344, in test_foreignkey
    reviews = [obj.book.title for obj in qs]
  File "C:\Python26\lib\site-packages\django_versions\trunk\django\db\models\fie
lds\related.py", line 379, in __get__
    raise self.field.rel.to.DoesNotExist
DoesNotExist

[milosu]

shorter and still working patch, which does not lead to deadlock while resolving pkey

[Luke Plant <L.Plant.98@…>]

In [4fea46a030689d7ae774ee0217dbce28de5a1b29]:

Fixed #18309 - Prefetch related does not work for fkey to multitable inherited model

Thanks to milosu for the report, tests and initial patch.