ycb_django_pr14089

what a new run launched now would send

Allow calling reversed() on an OrderedSet
Description
	
Currently, ​OrderedSet isn't reversible (i.e. allowed to be passed as an argument to Python's ​reversed()). This would be natural to support given that OrderedSet is ordered. This should be straightforward to add by adding a __reversed__() method to OrderedSet.

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describes, keeping the diff focused — no drive-by refactors.

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