This has been going on a while but last build I observed it in is eb47335.
On beginning of new game, all wander spawns make a beeline NW as far as possible. Unless they’re distracted by noise, they just keep heading that way for no apparent reason.
I just encountered this bug too. Started off in the middle of nowhere, started walking southeast, and met a giant wall of zombies.
Yup, that’s just one of their many quirks at the moment.