The bug

If a warden gets angry at a zombie, and said zombie transforms into a drowned before the warden can kill it, the warden will not remain angry at this drowned and will need to become aggressive toward it a second time.

How to reproduce

I don't know of a good setup to reproduce this in consistently. Zombies take around 46 seconds to transform once submerged, so summoning a warden in at the 25 second mark is probably best.

Expected results

The warden would remain angry even when the targeted zombie becomes a drowned.

Actual results

It loses its target.