while player is in a lake of water zombies do not agro, instead zombies home in on a hole with flowing water and stay there. leaving the water causes them to agro on player, jumping back in water causes them to home in on hole with flowing water again.
Is this still a concern in the current Minecraft version? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.