If I install all updates from site_name/update.php, and after change the system.schema_version from 7005 to 7003 using (to reinstall updates 7004 and 7005)
UPDATE system SET schema_version = 7003 WHERE name = 'test';
I then try to run site_name/update.php but it not run because the fields that
hook_update_N()adds already exists. And I see when access update.php after error that 2 updates exists.
After I restore system.schema_version to its initially value (7005)
Are the updates 7004 and 7005 now installed or not?