create empty backports source as soon as ubuntu is released

Currently, the sources.list provided by Ubuntu Breezy contains appropriate
backports sources:

#deb http://gb.archive.ubuntu.com/ubuntu breezy-backports main restricted
universe multiverse
#deb-src http://gb.archive.ubuntu.com/ubuntu breezy-backports main restricted
universe multiverse

However, these sources doesn't exist now (since no package has been backported
yet).

Isn't possible to create these sources with empty indexes so they can be checked
without issuing an error. Currently in Update-Manager, it gives 2 errors: first,
"Could not download all repository indexes", after that, "The following problems
were found on your system".

I would suggest to create the corresponding directories and indexes for
*-backports as soon as a version of Ubuntu is released as currently occurs with
*-security and *-updates.