[DebianGIS] aptitude warning of untrusted source

[Neil Best <n-best@neiu.edu>]

Hello, DebianGIS folks.  I am running sid on a particular box with the
DebianGIS repository in my sources.list.  Aptitude gives me a warning
about package qgis being from an untrusted source and apparently won't
allow me to install it.  What's more, my previously installed qgis
appears to have been purged.  I trolled the net and docs for a
reasonable amount of time and the only guidance that seemed relevant was
to add "APT::Get::AllowUnauthenticated 1 ;" to apt.conf, but that didn't
seem to have any effect.  Suggestions, anyone?  I will exhibit proper
sheepishness if anyone can provide the link that I should have followed.
Thanks.

Neil