Containment Priest is exiling creatures that enter the battlefield at the same time it does

Twice I've exiled [[Containment Priest]] with another creature using [[Lagrella, the Magpie]], and the priest exiled the other creature upon reentry both times. One time it was a pair of priests, which was interesting because only one of them got exiled upon reentry and the other remained on the battlefield.

Reproduce the interaction by exiling Containment Priest with another creature using Lagrella, the Magpie, including the case with two Priests. Inspect the implementations or rules handling for these cards and verify that creatures entering simultaneously do not incorrectly exile one another; confirm both reported scenarios are fixed.

Written by the indexing model from the issue text.