Change default to single column UI (mastodon#10847)

Keep current setting for users who were active within the last month

config/settings.yml

@@ -31,7 +31,7 @@ defaults: &defaults
  noindex: false
  theme: 'default'
  aggregate_reblogs: true
- advanced_layout: true
+ advanced_layout: false
  notification_emails:
  follow: false
  reblog: false

db/migrate/20190529143559_preserve_old_layout_for_existing_users.rb

@@ -0,0 +1,17 @@
+class PreserveOldLayoutForExistingUsers < ActiveRecord::Migration[5.2]
+ disable_ddl_transaction!
+
+ def up
+ # Assume that currently active users are already using the layout that they
+ # want to use, therefore ensure that it is saved explicitly and not based
+ # on the to-be-changed default
+
+ User.where(User.arel_table[:current_sign_in_at].gteq(1.month.ago)).find_each do |user|
+ next if Setting.unscoped.where(thing_type: 'User', thing_id: user.id, var: 'advanced_layout').exists?
+ user.settings.advanced_layout = true
+ end
+ end
+
+ def down
+ end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2019_05_19_130537) do
+ActiveRecord::Schema.define(version: 2019_05_29_143559) do
 
  # These are extensions that must be enabled in order to support this database
  enable_extension "plpgsql"