If the pane is still on all_window_panes but not actually connected to window or session (which can happen if it is killed during a command sequence and something else has a reference), fall back to the best effort. Fixes "tmux killw\; detach" for Rudis Muiznieks.
If the pane is still on all_window_panes but not actually connected to
window or session (which can happen if it is killed during a command
sequence and something else has a reference), fall back to the best
effort. Fixes "tmux killw\; detach" for Rudis Muiznieks.

klaxalk/tmux,klaxalk/tmux,klaxalk/tmux,klaxalk/tmux,klaxalk/tmux