Filter not displayed when admin.RelatedOnlyFieldListFilter is used for auth.models.User

[rvernica]

In a model where a field is a foreign keys to auth.models.User, admin.RelatedOnlyFieldListFilter does not display a filter. Something like:

class Foo(models.Model):
  bar = models.ForeignKey(auth.models.User, on_delete=models.CASCADE)

And ModelAdmin uses RelatedOnlyFieldListFilter for the foreign key:

class FooAdmin(admin.ModelAdmin):
  list_display = ('bar',)
  list_filter = (('bar', admin.RelatedOnlyFieldListFilter),)

No filter is displayed in the UI in the right side-bar. No error message is displayed. If list_filter is changed to:

  list_filter = ('bar',)

It works as expected.

[Mariusz Felisiak]

Everything works for me on the current master (checked at 49fb3f5f3ed8b37f2ae02d0fdc6980c4152c58e3). Maybe you have only one user related with Foo. List filter with only one value will not be displayed.