Problem
Killing a shopkeeper (at least Munxip) with the Petrification spell in your first try doesn't prevent him from yelling and summoning thugs. The following exchange should speak for itself:

"You focus your magical energies to release the spell. Which direction [89632147, Z = ABORT]?
Munxip, the human shopkeeper, is petrified. [+12902xp] Munxip, the human shopkeeper, yells: "Stop, ye thief!". Suddenly several figures appear out of nowhere! Suddenly several figures appear out of nowhere!"

How to reproduce it
Load a PC that can cast Petrification. Find a shopkeeper and use the spell on him. If you get it right in the first attempt, you'll see the illogical message above, and thugs will be summoned.

Notes
When this happens, shopkeepers should turn into a statue and thugs shouldn't be summoned. For those who think this is unbalanced, Petrification is a very rare and expensive spell and it's not guaranteed to work the first time (and will turn the shopkeeper hostile when it doesn't, although he can be calmed).

The "Suddenly several figures appear out of nowhere! Suddenly several figures appear out of nowhere!" is rendered verbatim from the game.