Hexproof granted after been targetted bug.

I have [[Nightveil Predator]] in play with a counter on it (a creature with hexproof). My commander [[Volrath, the Shapestealer]] is targeted by [[Angel of Serenity]] ETB to exile it. In response I activate Volrath to become a copy of Nightveil so that my commander gains hexproof and is saved. When the ability resolved my commander was exiled anyway.

No source file or test is named. Start by reproducing the interaction between Nightveil Predator, Volrath, and Angel of Serenity, then trace how the target and hexproof are handled when the exile ability resolves. Done means the commander remains on the battlefield when it becomes a hexproof copy before resolution.

Written by the indexing model from the issue text.