Code review comment for lp:~widelands-dev/widelands/bug-1674243-crash_with_save_game

I guess that sort of situation could help with a bit of testing, yes.

Nodes are rediscovered if a worker or ship passes by them, or if a building is built nearby.

It can also be triggered by Lua code as in https://code.launchpad.net/~widelands-dev/widelands/bug-1687100-reveal_fields/+merge/323721, but that's the rarer case.

Lua change terrain is used in the Trident of Fire multiplayer scenario, and in the Atlantean campaign scenario.