Namespaces.owner_id can be null

db/migrate/20130926081215_change_owner_id_for_group.rb

+class ChangeOwnerIdForGroup < ActiveRecord::Migration
+  def up
+    change_column :namespaces, :owner_id, :integer, null: true
+  end
+
+  def down
+    change_column :namespaces, :owner_id, :integer, null: false
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended to check this file into your version control system.
 
-ActiveRecord::Schema.define(:version => 20130909132950) do
+ActiveRecord::Schema.define(:version => 20130926081215) do
 
   create_table "deploy_keys_projects", :force => true do |t|
     t.integer  "deploy_key_id", :null => false
@@ -129,7 +129,7 @@ ActiveRecord::Schema.define(:version => 20130909132950) do
   create_table "namespaces", :force => true do |t|
     t.string   "name",                        :null => false
     t.string   "path",                        :null => false
-    t.integer  "owner_id",                    :null => false
+    t.integer  "owner_id"
     t.datetime "created_at",                  :null => false
     t.datetime "updated_at",                  :null => false
     t.string   "type"