As a workaround, I created the file 01x11-has_option (find it attached)
and placed it in /etc/X11/Xsession.d/. It defines has_option unless it
is already defined somewhere else. ssh-agent now runs in the background
on startup again.
** Attachment added: "/etc/X11/Xsession.d/01x11-has_option"
Looks like /etc/X11/Xsession is not executed, but the files in
/etc/X11/Xsession.d/ are sourced somehow. My best guess is that there's
some other mechanism emulating Xsession's behaviour but without defining
has_option.
Maybe this is a pending bug introduced in an earlier version of Ubuntu
that ha
