db/migrate/20190919145012_user_roles.rb in zizia-4.0.4.alpha.01 vs db/migrate/20190919145012_user_roles.rb in zizia-4.1.0.alpha.01

@@ -1,15 +1,17 @@
 class UserRoles < ActiveRecord::Migration[5.0]
   def up
-    create_table :roles do |t|
-      t.string :name
+    unless table_exists?(:roles)
+      create_table :roles do |t|
+        t.string :name
+      end
+      create_table :roles_users, :id => false do |t|
+        t.references :role
+        t.references :user
+      end
+      add_index :roles_users, [:role_id, :user_id]
+      add_index :roles_users, [:user_id, :role_id]
     end
-    create_table :roles_users, :id => false do |t|
-      t.references :role
-      t.references :user
-    end
-    add_index :roles_users, [:role_id, :user_id]
-    add_index :roles_users, [:user_id, :role_id]
   end
 
   def down
     drop_table :roles_users
     drop_table :roles