[bug r2762] No tile refresh when I remove city

[z9999+]

r2762
When I remove city, some of tiles under buildings doesn't refresh, and ugly hole remains.

[Dwachs]

should work in 2766

[wernieman]

At Example:
- Delete a building
- Try to build a road/track on the same place
Nothing happens

I think when deleting a building, the place will not be not "free"

(It is the same with player-building)

I test with 1742, there it works

P.S: When I save and reload, then it works ...

[Dwachs]

is related to z9999's bug report and should be fixed as well.