Have you ever tried to sap an Engineer building, only to find that it was turned off?

No?

Well, this should solve the problem anyways. With restoring a unused (or previously used in very early TF2, but disabled for an undocumented reason. I've heard conflicting sources say both options) where Spy flicks the Sapper on so he can properly sap the enemy's buildings.

This change only affects the Stock Sapper and it's festive variant, as those are the only two with proper switches.

For Valve: Contains a readme file that contains a detailed explaination on how to re-implement it into the game.

Credits:
Sae35™: Made the community fix and the showcase video.
azzy: For creating a fix preventing Spy from having a third arm.