os::debian: Do not override locale if set

manifests/os/debian.pp

@@ -173,6 +173,7 @@ class base::os::debian (
   # Ensure this file exists, containing only a comment.
   file { '/etc/default/locale':
     ensure  => present,
+    replace => false,
     content => "# Not used but required by PAM.\n",
   }