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Changes between Initial Version and Version 1 of Ticket #36388, comment 10

initial	v1
3	3	Please have a look at [https://github.com/django/django/pull/19471#discussion_r2091852049 this comment]. The fact the tests are passing is not a good indicative that the right thing is happening here as the adjusted test I provided demonstrates (it does a `UNION` against itself which is not safe when `all` is used).
4	4
5		I still believe that the right way of fixing this is to adjust `QuerySet.union` to return `self` when `not other_qs`.
	5	I still believe that the right way of fixing this is to adjust `QuerySet.union` to return `self` when `not other_qs` as the compilation layer is not equipped to deal with an empty combination of queries and it's just faster to avoid the query cloning if we can.