El mismo error te dice que tienes un problema de indentación.
QuestionAdmin debería ser.
Código Python:
Ver originalclass QuestionAdmin(admin.ModelAdmin):
fieldsets = [
(None, {'fields': ['question_text']}),
('Date information', {'fields': ['pub_date'], 'classes': ['collapse']}),
]
inlines = [ChoiceInline]
list_display = ('question_text', 'pub_date', 'was_published_recently')
list_filter = ['pub_date']
search_fields = ['question_text']
No combines espacios y tabs.