A17 Friendlies stuck on map edge, can't find path to insect threat

[rob-air]

gameVersion 0.17.1557 rev1153
_{windows, steam, no mods, french locale}

This issue looks a lot like to these two:
https://ludeon.com/forums/index.php?topic=35099.0
https://ludeon.com/forums/index.php?topic=33285.0
...which are said to be fixed for A18. But I couldn't find anything relating to my situation on Mantis, and I'm told it can't hurt to report the heck out of those pesky bugs

^SETUP
My colony has a few insect hives in a room that is reachable (deadfall traps in the only corridor leading to it, though) but out of the base zone.
Insects are keeping to themselves, so am I, no ongoing raid or any form of combat anywhere on that map.
I have two pawns in a caravan/raiding party on a resource deposit about 30 tiles away. I can't remember if fighting was still going on there when the next thing happened.

^IGNITION
A friendly caravan arrives at the colony, immediately says they'll help with the threat. I don't see a threat at home so I ignore them to focus on getting my raiding party back, and doing so I fail to notice them getting stuck near the edge of the map just outside my base.
I didn't send any request for military help, and I'm pretty sure it wasn't the response to a trade caravan request from me.

^LIFT-OFF
At that point the game is laggy as hell and nearly unresponsive so as soon as my raiding party is back home, I have to try and look for the issue, I figured there was some ugly deal going on somewhere. That's when I found them all glitching around like Michael Jackson on go-juice.

^FAIL
They all had the status "waiting" and were still able to engage in social talk. As the game was too laggy to keep playing I didn't have the possibility of letting them starve to death there, like I've seen in the other two posts about this issue. I should mention at that point that my computer is getting pretty old and with a colony of 20+ pawns it can get a bit slow sometimes at the maximum gamespeed, but still absolutely playable: nothing like this.

^FALL
So here is what I found in the log:
Edie pathing from (251, 0, 83) to Thing_Megascarab2684685 hit search limit of 160000 cells.
Obviously repeated for all of them, many times each.
(savefile is at that point)

^BURN
I tried extending the base zone to include the hive room, that didn't do.
I tried waking them up by means of live mortar shells on top of their dreamy heads, that worked to some extent but isn't very diplomatic.
Finally I found a middle ground, using the debug menu to set them all in a fleeing mood. Performance was back up as soon as they stopped looking for an apparently impossible path. They left the map mentally harmed and still not knowing what had happened, but walking again and in a somewhat straight line.

^REPEAT
Savefile.zip (1MB) is here, savefile.rws (17MB) is here if you don't trust my zipping.


Enjoy! and please don't report me for filling a bugreport with unnecessary bad humor: I'm not a bug, I'm a feature.

[ison]

Thanks for the detailed write-up, it looks like it's already fixed in A18, though the path finding performance is still not that great, but at least it's not causing any errors. I'll see if this can be improved.