Merge ~j.kylmala/cloud-init:disable-proprietary-repositories into cloud-init:master

[Joonas Kylmälä]

Remove non-free repositories from Debian template.

The Debian GNU/Linux distribution doesn't come offically with the
non-free repositories enabled. Therefore, we want to disable those in
the cloud-init template.

LP: #1700091

[Server Team CI bot (server-team-bot)]

PASSED: Continuous integration, rev:81f3bf319068a4054dfdbfccb8b4ae01424ca3ee
https://jenkins.ubuntu.com/server/job/cloud-init-ci/171/
Executed test runs:
    SUCCESS: Checkout
    SUCCESS: Unit & Style Tests
    SUCCESS: Ubuntu LTS: Build
    SUCCESS: Ubuntu LTS: Integration
    SUCCESS: MAAS Compatability Testing
    IN_PROGRESS: Declarative: Post Actions

Click here to trigger a rebuild:
https://jenkins.ubuntu.com/server/job/cloud-init-ci/171/rebuild

review: Approve (continuous-integration)

diff --git a/templates/sources.list.debian.tmpl b/templates/sources.list.debian.tmpl
index d64ace4..e7ef9ed 100644
--- a/templates/sources.list.debian.tmpl
+++ b/templates/sources.list.debian.tmpl
@@ -10,15 +10,15 @@
 
 # See http://www.debian.org/releases/stable/i386/release-notes/ch-upgrading.html
 # for how to upgrade to newer versions of the distribution.
-deb {{mirror}} {{codename}} main contrib non-free
-deb-src {{mirror}} {{codename}} main contrib non-free
+deb {{mirror}} {{codename}} main
+deb-src {{mirror}} {{codename}} main
 
 ## Major bug fix updates produced after the final release of the
 ## distribution.
-deb {{security}} {{codename}}/updates main contrib non-free
-deb-src {{security}} {{codename}}/updates main contrib non-free
-deb {{mirror}} {{codename}}-updates main contrib non-free
-deb-src {{mirror}} {{codename}}-updates main contrib non-free
+deb {{security}} {{codename}}/updates main
+deb-src {{security}} {{codename}}/updates main
+deb {{mirror}} {{codename}}-updates main
+deb-src {{mirror}} {{codename}}-updates main
 
 ## Uncomment the following two lines to add software from the 'backports'
 ## repository.
@@ -26,5 +26,5 @@ deb-src {{mirror}} {{codename}}-updates main contrib non-free
 ## N.B. software from this repository may not have been tested as
 ## extensively as that contained in the main release, although it includes
 ## newer versions of some applications which may provide useful features.
-deb {{mirror}} {{codename}}-backports main contrib non-free
-deb-src {{mirror}} {{codename}}-backports main contrib non-free
+deb {{mirror}} {{codename}}-backports main
+deb-src {{mirror}} {{codename}}-backports main