And now, suddenly, it just works again.

root@saegusa:~# snap install wekan
wekan 0.77-29-g9e62584 from 'xet7' installed

root@battra:~# snap install wekan
2018/03/02 16:39:13.986937 cmd.go:212: DEBUG: restarting into "/snap/core/current/usr/bin/snap"
wekan 0.77-29-g9e62584 from 'xet7' installed

Darn it, I was hoping to catch the exact cause. Unless you guys already found and fixed it?

What’s changed on my end since I posted the last comment a week ago is the core snap updating from 4017 to 4110.