re-factor debian-build.erb

templates/etc/apt/preferences.d/debian-build.erb

 # We want the most recent version of several debian build tools.
+<%-
+  packages_to_pin = [
+    'debhelper',
+    'dpatch',
+    'debootstrap',
+    'dh-autoreconf',
+    'dh-strip-nondeterminism',
+    'libfile-stripnondeterminism-perl',
+    'pbuilder',
+    'quilt',
+  ]
 
-Package: debhelper
-Pin: release a=<%= @lsbdistcodename %>-backports
-Pin-Priority: 991
-
-# The changes come thick-and-fast with pbuilder, so we get it from
-# <%= @lsbdistcodename %>-backports.
-Package: pbuilder
-Pin: release a=<%= @lsbdistcodename %>-backports
-Pin-Priority: 995
-
-# Along with pbuilder, we need to get the very latest debootstrap.
-Package: debootstrap
-Pin: release a=<%= @lsbdistcodename %>-backports
-Pin-Priority: 995
+  packages_to_pin.each |package_to_pin| do
+-%>
 
-# More debhelper packages needed
-Package: dh-autoreconf
+Package: <%= package_to_pin %>
 Pin: release a=<%= @lsbdistcodename %>-backports
-Pin-Priority: 995
-
-Package: dh-strip-nondeterminism
-Pin: release a=<%= @lsbdistcodename %>-backports
-Pin-Priority: 995
-
-Package: libfile-stripnondeterminism-perl
-Pin: release a=<%= @lsbdistcodename %>-backports
-Pin-Priority: 995
+Pin-Priority: 991
+<%- end %>