mozilla.d.net APT archive unsigned?

[Lars Wirzenius]

I have this in my sources.list:

    deb http://mozilla.debian.net/ jessie-backports iceweasel-release

This morning, after an "apt-get update", I get this:

    liw at exolobe1$ sudo apt-get dist-upgrade
    Reading package lists... Done
    Building dependency tree       
    Reading state information... Done
    Calculating upgrade... Done
    The following packages will be upgraded:
      iceweasel iceweasel-l10n-en-gb
    2 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
    Need to get 41.1 MB of archives.
    After this operation, 2,366 kB of additional disk space will be used.
    Do you want to continue? [Y/n] 
    WARNING: The following packages cannot be authenticated!
      iceweasel-l10n-en-gb iceweasel
    Install these packages without verification? [y/N] n
    E: Some packages could not be authenticated

It looks to me like the Mozilla APT archive is unsigned today. What's
up?

-- 
sic transit disci mundi, ergo obnam