Bukkit

What steps will reproduce the problem?
1. make a chestshop
2. edit the shop sign with simple sign edit
3. change the name (top line) to whatever you want, any player and even the admin shop.

What is the expected output? What do you see instead?
Chest shop throws an error saying you can't make that shop

What version of the product are you using?
2.2 SSE and CS 3.7.8

Do you have an error log of what happened?
No error in console/log

Please provide any additional information below.
After editing the sign you can buy/sell to it, draining the players account, or with an admin shop get really cheap items or mass amounts of money.
Recognizing a chestshop and denying editing the first line would be nice if the player does not have the proper chestshop permissions.

Talked to Acrobot (CS dev) and he said that SSE should be throwing a sign change event, but it's not.