id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
28378	QuerySet.union() with queryset that raises EmptyResultSet results in an empty set	Jon Dufresne	nobody	"Similar and followup to ticket #28293. Tested on Django 1.11.3.

As QuerySet.union() uses the SQL UNION operator, I would expect ""SET1 UNION <EMPTY SET>"" to result in SET1. If the empty set is the results of [https://github.com/django/django/blob/5b450b84e14f42302f58ec1f15a67a368e64d85c/django/db/models/sql/where.py#L97 EmpytResultSet being raised], the `.uion()` result is an empty set, not SET1.

Example test case:

{{{
>>> import django
>>> django.__version__
'1.11.3'
>>> from django.contrib.auth.models import User
>>> qs1 = User.objects.all() 
>>> qs1.count()
100
>>> qs2 = User.objects.filter(pk__in=[])
>>> qs2.count()
0
>>> list(qs1.union(qs2))
[]
}}}"	Bug	new	Database layer (models, ORM)	1.11	Normal				Unreviewed	0	0	0	0	0	0