Motivation / Problem

As described in #7604, a bug that existed since TTO. It is a funny little bug, and depending on how lucky you are, houses could wander off endlessly. This simple approach resolve the wandering around.

Description

When a multi-tile house is rebuild, it always used the most northern
tile to build the new house. This can very easily lead to houses
wandering off in the north-ish direction (either NW or NE).

To prevent this, pick the tile closest to town center when rebuilding
on a multi-tile house. This still means a house can be build away
from a road, but it is no longer wandering around finding another
town to call home.

If you want to see for yourself that this works, best to use the following savegame:
issue-7604.zip

It is somewhat prepared to show the worst of this all ;) Just load it in, unpause, fast forward, and once in a while send some funds to the town. If you want to test this faster, change line 624 to:

t->time_until_rebuild = 1;

And line 629 to:

if (true || GB(r, 24, 8) >= 12) {

Now you have some speedy rebuilds on your hands!

Limitations

• This does not prevent a house from being build while not next to a road. That could be added, but requires a lot more complex code, which was not worth the effort in my opinion.

Checklist for review

Some things are not automated, and forgotten often. This list is a reminder for the reviewers.

• The bug fix is important enough to be backported? (label: 'backport requested')
• This PR affects the save game format? (label 'savegame upgrade')
• This PR affects the GS/AI API? (label 'needs review: Script API')
  • ai_changelog.hpp, gs_changelog.hpp need updating.
  • The compatibility wrappers (compat_*.nut) need updating.
• This PR affects the NewGRF API? (label 'needs review: NewGRF')
  • PR must be added to API tracker