Signature of wheezy's linux source package

[Matthias Großmann <grossmms@googlemail.com>]

Hi All,

after downloading the most recent linux source package for wheezy
on my wheezy system, I noticed that dpkg-source fails to verify its 
signature:

$ dpkg-source -x linux_3.2.57-3+deb7u2.dsc 
gpgv: Signature made Thu Jun  5 10:38:20 2014 CEST using RSA key ID 1343CF44
gpgv: Can't check signature: public key not found
dpkg-source: warning: failed to verify signature on ./linux_3.2.57-3+deb7u2.dsc

The debian-keyring package is installed. Apparently, the key used for signing
the linux source package is included in sid's version of debian-keyring
(2014.04.25), but not in wheezy's (2013.04.21).

I would expect everything required to verify packages in wheezy to be
included in wheezy, so I guess this is a bug. Or am I missing something?

TIA,
 Matthias Grossmann