Rake: enable trusted_device for some gestionnaire

lib/tasks/2018_11_08_activate_trusted_device_for_a-f.rake

@@ -0,0 +1,8 @@
+namespace :'activate_trusted_device_for_a-f' do
+  task run: :environment do
+    letters_a_to_f = ('a'..'f').to_a
+    Gestionnaire
+      .where("substr(email, 1, 1) IN (?)", letters_a_to_f)
+      .update_all(features: { "enable_email_login_token" => true })
+  end
+end