If tmux is started with a start directory (e.g. /usr/bin/tmux
new-session -c /some/start/dir), then basename in
__done_is_tmux_window_active will fail to extract tmux and thus fail to
identify the process as tmux.
Tmux also starts fish as a login shell, leading to the process name
being '-fish'. When passing this to basename, it interpets the hyphen as
an option being passed to basename.
If tmux is started with a start directory (e.g. /usr/bin/tmux new-session -c /some/start/dir), then basename in __done_is_tmux_window_active will fail to extract tmux and thus fail to identify the process as tmux.
Tmux also starts fish as a login shell, leading to the process name being '-fish'. When passing this to basename, it interpets the hyphen as an option being passed to basename.