[Xfce] firefox-esr keeps reloading previous tabs on startup

[Mike Kupfer <m.kupfer@acm.org>]

Is anyone else on Jessie (x86_64) seeing a problem where Firefox
(45.2.0esr-1~deb8u1) wants to reload the tabs from the previous session,
even when the preferences are set not to do that?

I normally use "show a blank page" on startup, but I was getting either
the previous tabs or the "this is embarassing" screen (where FF tells me
it was unable to restore the tabs).

I changed to "show my home page", and I would briefly see my home page
before it was replaced by the "this is embarassing" screen.

The problem isn't 100% reproducible, but it's close to it.

I only have one extension (NoScript).  Disabling it didn't help.

I have a few plug-ins installed, but they are all set to Never
Activate.

The problem seems tied to using exo-open.  I see the problem when I
start Firefox via the "Web browser" entry in the main Xfce menu.  I
don't see the problem if I invoke Firefox from the shell, Alt-F2, or a
customer launcher (which just runs "firefox").

Any ideas?

thanks,
mike