Comment (by Zach Etienne):

No it’s fully backportable for current Baikal* thorns, as it produces correct behavior in all cases Baikal* supports. (Currently Baikal* does not support symmetries, as was the nature of the problem with the other ticket.) We confirmed this patch fixes a bug in current Baikal*.

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2432/backport-baikal-boundary-handling-fix-to