Can't cure zombie plague with cure plague potion

Turns out it's (nearly?) impossible to cure yourself with a cure plague potion when inflicted with the zombie plague. The cast time on the potion is longer than the tick time on the DoT. When the DoT ticks, it interrupts the plague potion and starts the cooldown on the potion.

So it's either train in purity and get it high enough to have a reasonable chance of success, or die. The potion is more or less worthless.