Byobu 6.5+ autostart broken with fish shell

[David Mehren]

Since byobu 6.5, the shell spawned by byobu-shell is started as a login shell using -l (https://github.com/dustinkirkland/byobu/commit/4a2ebccb627055e3605e39d300c6cf23d12939a1). This breaks byobu autostart with fish, as the autostart code in config.fish uses status --is-login to determine if fish runs inside byobu already. The autostart code only executes byobu-launcher if fish is a login shell (and interactive, but that doesn't seem relevant here). As byobu then starts fish again as a login shell, byobu starts again, which leads to tmux refusing to work with "sessions should be nested with care, unset $TMUX to force" and everything quits.

I now cannot SSH into my server with byobu 6.5+ and autostart enabled, as byobu immediately quits.

This has also been experienced by another user in https://github.com/dustinkirkland/byobu/commit/4a2ebccb627055e3605e39d300c6cf23d12939a1#commitcomment-140698811

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.