Set a default locale of C.UTF-8 in the cloud images.

debian/changelog

@@ -1,7 +1,11 @@
 livecd-rootfs (2.449) UNRELEASED; urgency=medium
 
+  [ Balint Reczey ]
   * Use VMDKstream in a more future-proof way
 
+  [ Steve Langasek ]
+  * Set a default locale of C.UTF-8 in the cloud images.
+
  -- Balint Reczey <rbalint@ubuntu.com>  Mon, 24 Jul 2017 20:39:35 +0200
 
 livecd-rootfs (2.448) artful; urgency=medium

live-build/ubuntu-cpc/hooks/999-cpc-fixes.chroot

@@ -89,6 +89,12 @@ _xchroot "${rootd}" sh -c 'rm -f /etc/ssh/ssh_host_[rd]sa_key*'
 ## --------------
 _xchroot "${rootd}" locale-gen en_US.utf8
 
+## --------------
+# We continue to pre-generate en_US.UTF-8 locale above, but the default locale
+# should be C.UTF-8 for 17.10 and later.  For earlier releases, cloud-init may
+# override this.
+echo LANG="C.UTF-8" > "${rootd}/etc/default/locale"
+
 ## --------------
 # set cloud-init to be on
 values="NoCloud, ConfigDrive, AltCloud, OVF, MAAS, Ec2, None"