I confirm this problem, as reported by Peter Denison. I observed it last week too, but did not report it immediately expecting that the file at http://people.debian.org/~bartm/ would soon be fixed. It has now been missing for about 1 week.
This bug can be reproduced equally with
update-flashplugin-nonfree --install
and with
dpkg-reconfigure flashplugin-nonfree
Thank you in advance for fixing!
Nick
