Fixed: project copy doesn't copy group memberships (#3975).

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@3250 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/models/member_role.rb

@@ -30,6 +30,10 @@ class MemberRole < ActiveRecord::Base
     errors.add :role_id, :invalid if role && !role.member?
   end
   
+  def inherited?
+    !inherited_from.nil?
+  end
+  
   private
   
   def remove_member_if_empty