All installed packages disappeared from aptitude

[Patrick Wiseman <pwiseman@gmail.com>]

Hello:

I just updated and upgraded a 'testing' system (so listed in
sources.list) and aptitude shows no installed packages. Here's a
typical aptitude entry:

i A apache2 2.4.10-9 <none>

and another:

ih perl 5.20.1-5 <none>

(The 'h' because I put it on hold when I saw it was among many
potentially broken packages.)

As you see, 'i' indicates that the packages _are_ installed, but it's
the '<none>' which concerns me, because on its entry page, aptitude
lists NO installed packages. If I reboot, I suspect everything's going
to disappear.

Is there any way to recover, without rebooting, from this potential disaster?

Thanks
Patrick