The APT pinning we ship does not support that, and this seems a bit too much of
a corner case to me to deserve being supported out-of-the-box.
Anyone willing to use current release + next release + next release backports
(e.g. Lenny + Squeeze + squeeze-backports) can anyway do so using
apt::sources_list and apt::preferences_snippet.
https://labs.riseup.net/code/issues/2856 is the bug that triggered this change.
<% end -%>
<% end -%>
-# backports
-<% if (next_release == "testing" || next_release == "unstable" || next_release == "experimental") -%>
-# There is no backports archive for <%= next_release %>
-<% else -%>
-deb <%= backports_url %> <%= next_codename %>-backports <%= repos %>
-<% if include_src then -%>
-deb-src <%= backports_url %> <%= next_codename %>-backports <%= repos %>
-<% end -%>
-<% end -%>
-
<% if use_volatile -%>
# volatile
<% if (next_release == "testing" || next_release == "unstable" || next_release == "experimental") -%>