Travis failing

[tony]

It's difficult to get a proper feedback loop going if CI isn't update

Even with the benefit of the admin typo fix at #330, tests still fail.

This needs to get squared away so new contributions can be verified

[tony]

./runtests.py --failfast --debug-mode
Using Python version 3.6.3 from /Users/me/work/python/django-polymorphic/.venv/bin/python
Using Django version 1.11.4 from /Users/me/work/python/django-polymorphic/.venv/lib/python3.6/site-packages/django
Creating test database for alias 'default'...
Creating test database for alias 'secondary'...
System check identified no issues (0 silenced).
.E
======================================================================
ERROR: test_admin_registration (polymorphic.tests.test_admin.PolymorphicAdminTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/me/work/python/django-polymorphic/polymorphic/tests/test_admin.py", line 37, in test_admin_registration
    self.admin_get_add(Model2A, qs='?ct_id={}'.format(ct_id))  # shows type page
  File "/Users/me/work/python/django-polymorphic/polymorphic/tests/admintestcase.py", line 93, in admin_get_add
    response = admin_instance.add_view(request)
  File "/Users/me/work/python/django-polymorphic/polymorphic/admin/parentadmin.py", line 199, in add_view
    return real_admin.add_view(request, form_url, extra_context)
  File "/Users/me/work/python/django-polymorphic/.venv/lib/python3.6/site-packages/django/contrib/admin/options.py", line 1508, in add_view
    return self.changeform_view(request, None, form_url, extra_context)
  File "/Users/me/work/python/django-polymorphic/.venv/lib/python3.6/site-packages/django/utils/decorators.py", line 67, in _wrapper
    return bound_func(*args, **kwargs)
  File "/Users/me/work/python/django-polymorphic/.venv/lib/python3.6/site-packages/django/utils/decorators.py", line 149, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "/Users/me/work/python/django-polymorphic/.venv/lib/python3.6/site-packages/django/utils/decorators.py", line 63, in bound_func
    return func.__get__(self, type(self))(*args2, **kwargs2)
  File "/Users/me/work/python/django-polymorphic/.venv/lib/python3.6/site-packages/django/contrib/admin/options.py", line 1408, in changeform_view
    return self._changeform_view(request, object_id, form_url, extra_context)
  File "/Users/me/work/python/django-polymorphic/.venv/lib/python3.6/site-packages/django/contrib/admin/options.py", line 1437, in _changeform_view
    ModelForm = self.get_form(request, obj)
  File "/Users/me/work/python/django-polymorphic/polymorphic/admin/childadmin.py", line 65, in get_form
    return super(PolymorphicChildModelAdmin, self).get_form(request, obj, **kwargs)
  File "/Users/me/work/python/django-polymorphic/.venv/lib/python3.6/site-packages/django/contrib/admin/options.py", line 615, in get_form
    fields = flatten_fieldsets(self.get_fieldsets(request, obj))
  File "/Users/me/work/python/django-polymorphic/polymorphic/admin/childadmin.py", line 191, in get_fieldsets
    other_fields = self.get_subclass_fields(request, obj)
  File "/Users/me/work/python/django-polymorphic/polymorphic/admin/childadmin.py", line 209, in get_subclass_fields
    form = self.get_form(request, obj, exclude=exclude)
  File "/Users/me/work/python/django-polymorphic/polymorphic/admin/childadmin.py", line 65, in get_form
    return super(PolymorphicChildModelAdmin, self).get_form(request, obj, **kwargs)
  File "/Users/me/work/python/django-polymorphic/.venv/lib/python3.6/site-packages/django/contrib/admin/options.py", line 615, in get_form
    fields = flatten_fieldsets(self.get_fieldsets(request, obj))
  File "/Users/me/work/python/django-polymorphic/polymorphic/admin/childadmin.py", line 191, in get_fieldsets
    other_fields = self.get_subclass_fields(request, obj)
  File "/Users/me/work/python/django-polymorphic/polymorphic/admin/childadmin.py", line 209, in get_subclass_fields
    form = self.get_form(request, obj, exclude=exclude)
  File "/Users/me/work/python/django-polymorphic/polymorphic/admin/childadmin.py", lin

... snip ...

    return super(PolymorphicChildModelAdmin, self).get_form(request, obj, **kwargs)
  File "/Users/me/work/python/django-polymorphic/.venv/lib/python3.6/site-packages/django/contrib/admin/options.py", line 615, in get_form
    fields = flatten_fieldsets(self.get_fieldsets(request, obj))
  File "/Users/me/work/python/django-polymorphic/polymorphic/admin/childadmin.py", line 191, in get_fieldsets
    other_fields = self.get_subclass_fields(request, obj)
  File "/Users/me/work/python/django-polymorphic/polymorphic/admin/childadmin.py", line 209, in get_subclass_fields
    form = self.get_form(request, obj, exclude=exclude)
  File "/Users/me/work/python/django-polymorphic/polymorphic/admin/childadmin.py", line 65, in get_form
    return super(PolymorphicChildModelAdmin, self).get_form(request, obj, **kwargs)
RecursionError: maximum recursion depth exceeded in comparison

[tony]

It seems to have happened here: 02b71d8

https://travis-ci.org/django-polymorphic/django-polymorphic/builds

[tony]

See #322

[vdboor]

Fixed with merging #322