Duplication bug with External Overlay Display

[JMatthewman]

When using the external overlay display, inserters (also miniloaders from https://mods.factorio.com/mod/miniloader) can remove the overlay items from the factory; when a player enters the factory the previously set overlay items re-appear, allowing duplication of any items which had been placed in the overlay items chest.

Steps to reproduce:

1. Build a factory
2. Place a single cog in the left hand 'factory overlay controller' chest
3. Place an inserter taking out of any of the middle 4 positions of the left hand side of the factory, placing into a chest
4. Your single cog will be removed from the factory, and placed into the chest
5. Walk into your factory, the 'factory overlay controller' chest will still contain the cog
6. Walk out of the factory again, the inserter will remove another cog
7. Your single cog originally placed in the overlay controller has now been turned into 3 cogs

This works with any item, or any amount of items, ie a stack of cogs placed in the overlay controller will allow you to extract a full stack of cogs between entering & exiting the factory.

[JMatthewman]

ah, this is actually a duplicate of #37