Comment 1 for bug 1662265

I worked around this issue by using "list-sessions" to work out if there are any open sessions, then calling the appropriate command:

---------
#!/bin/bash

byobu-tmux list-sessions
if [ "$?" -eq 0 ]; then
  tmuxCmd='att'
else
  tmuxCmd='new'
fi
byobu-tmux $tmuxCmd
---------