When running the upgrade switch, I get a number of failures unless I delete the following entries from my database:

delete from mantis_project_user_list_table where project_id=0000005 and user_id=0000000;
delete from mantis_project_user_list_table where project_id=0000000 and user_id=0000040;
delete from mantis_project_user_list_table where project_id=0000000 and user_id=0000039;
delete from mantis_project_user_list_table where project_id=0000008 and user_id=0000000;
delete from mantis_project_user_list_table where project_id=0000000 and user_id=0000051;