Lost graphical ssh-askpass with Xfce4 in forky

[Julian Gilbey <jdg@debian.org>]

Hello!

I upgraded my testing (forky) machine on Sunday and rebooted it with
the new kernel (previous reboot was on 31st August), and now when I
run "ssh remote.machine" in a terminal, I am no longer presented with
a graphical interface to enter my ssh key passphrase to add it to the
session keyring.  I cannot fathom what might have changed in the
upgrade to cause this, so I'm asking here first rather than reporting
a vague bug to the BTS against - well I'm really not sure....  There's
no obvious package that was upgraded between reboots that would have
been likely to cause this: a few possible candidates are libssh-4 and
the xserver-xorg packages.  I already had ssh-askpass installed, and
installing ssh-askpass-gnome didn't help.  I do have the session
running under ssh-agent; manually running ssh-add in a terminal works,
and adds the key to the keyring even for running ssh from a different
terminal.

Looking in .xsession-errors, the only relevant message is:

xfce4-session-Message: 18:07:24.229: GNOME compatibility is enabled and gnome-keyring-daemon is found on the system. Skipping gpg/ssh-agent startup.

Switching off GNOME compatibility didn't help, and my backups show
that this message appeared in .xsession-errors even before the
upgrade, so there's no change here.

I'm stumped.  Could anyone suggest where to look to find the cause of
this changed behaviour?

Best wishes,

   Julian