Julius: Amphitheater glitch on Tarraco

[falconepl]

Describe the bug
A building glitch shows up on the Tarraco map whenever the save is loaded. Sometimes it appears instantly after the save is loaded, sometimes it takes a few seconds to show up

To Reproduce

1. Load the save file provided

Expected behavior
We should not see the boxed amphitheater near the earthquake cracks. There's no building there

Saved games
Julius-V-01.zip

Screenshots

Additional context
The red blocks on earthquake cracks don't show up every time (not for every save file that contains the amphitheater glitch). But the glitch for the amphitheater appears every single time and stays in its place even when restarting the game

[crudelios]

I think I found the reason for both glitches.

Steps to reproduce:

• Load a new Tarraco scenario
• Place buildings on spots where the earthquake will destroy them
• Let the quake destroy the buildings
• Create many new buildings anywhere you wish
• Select the clear land button and hover your mouse over the cracks in the land tiles. The new buildings will also be highlighted in red

I'm thinking this bug happens because the cracks in the land never really remove the building ID from the tile, even though the ID is freed for a new building. So when a new building is created with the same ID, julius considers the building to also be located on the earthquake tile where the original building with that ID was.

Also, upon further testing, I found this bug also happens on the original C3. The following is a sav file created exclusively with C3, and you can see that the red highlight bug exists.

earthquake2.zip

The bug has two main effects

• Because the visual feedback on delete relies on building ID's, it's very easy to spot which crack tile has the same ID as a new building
• If the new building with the same ID has an animation (such as a theater, reservoir, amphitheater as seen in the image, and even a colosseum - I tested), the animation will not only draw on the bulding, but in the crack tile with the same ID.

So, my question is: since this is a bug from the original game, should we fix it?

[bvschaik]

I think we should fix this. I'll work on it this evening: the fix itself is trivial (thanks @crudelios for debugging this!), but the tests should be updated as well.