I'm closing this one for three reasons:
1- Couldn't reproduce (classic answer)
Even after various tests... It's probably related to broken save file... I
tried a little with the teletransportator and it works roughly like this: If you
are on level 59 you can only go to level 0 by the label. If you are on level 0
you can go to level 59 by the teletransporter OR to where you was last by the
homing beacon. The beacon will always do city->last_place and the town warp will
always do city->HF.
2- Obstacle label "59-Teleporter" exists on levels.dat
You can grep it, this error can only happen if the label is missing on the
savegame -- if not, then it's really a very serious issue... I also gave a look
on all waypoints on the server room. They all are connected. The map validator
said the same.
3- It was from 0.15+git version, while we are at 0.16.1, I'm pretty sure it was
already dealt with.
Why? Because nobody else reported this... And the few were savegame issues...
If you belive this to be equivocated, or if you are sure the error persists, by
al means re-open the ticket.
I'm also marking myself as a watcher in case this gives problems in future.