Remote Mirrors should be disabled by default

db/migrate/20160530214349_make_remote_mirrors_disabled_by_default.rb

+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class MakeRemoteMirrorsDisabledByDefault < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  # When using the methods "add_concurrent_index" or "add_column_with_default"
+  # you must disable the use of transactions as these methods can not run in an
+  # existing transaction. When using "add_concurrent_index" make sure that this
+  # method is the _only_ method called in the migration, any other changes
+  # should go in a separate migration. This ensures that upon failure _only_ the
+  # index creation fails and can be retried or reverted easily.
+  #
+  # To disable transactions uncomment the following line and remove these
+  # comments:
+  # disable_ddl_transaction!
+
+  def up
+    change_column :remote_mirrors, :enabled, :boolean, default: false
+  end
+
+  def down
+    change_column :remote_mirrors, :enabled, :boolean, default: true
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20160509201028) do
+ActiveRecord::Schema.define(version: 20160530214349) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -922,7 +922,7 @@ ActiveRecord::Schema.define(version: 20160509201028) do
   create_table "remote_mirrors", force: :cascade do |t|
     t.integer  "project_id"
     t.string   "url"
-    t.boolean  "enabled",                    default: true
+    t.boolean  "enabled",                    default: false
     t.string   "update_status"
     t.datetime "last_update_at"
     t.datetime "last_successful_update_at"