No security updates available for s390x

[Stephen Powell <zlinuxman@wowway.com>]

After doing a fresh install of Debian Wheezy for s390x I discovered that
there is no security support available for this architecture.
"aptitude update" produced the following error messages:

W: Failed to fetch http://security.debian.org/dists/wheezy/updates/InRelease:
Unable to find expected entry 'main/binary-s390x/Packages' in Release file
(Wrong sources.list entry or malformed file)
E: Some index files failed to download. They have been ignored,
or old ones used instead.
E: Couldn't rebuild package cache

I checked /etc/apt/sources.list.  The entries are formed correctly:

deb http://security.debian.org/ wheezy/updates main contrib non-free
deb-src http://security.debian.org/ wheezy/updates main contrib non-free

A search of the internet using the above error messages produced no
useful hits.

Why is there no security support?

-- 
  .''`.     Stephen Powell    
 : :'  :
 `. `'`
   `-