If you know PHP, the following is not executing as expected:
$result = $installer-query( "select count(*) nb from users_users having count(*) 1" );
$row = $result-fetchRow();
On the first line, $result does not take the value expected, presumably because something goes wrong in query(). Make sure all PHP errors are reported (PHP setting error_reporting).
When I run this query in phpmyadmin I get
What is nb?
nb, is the count(*), in this case the number of users. But that patch is broken and wouldn't do anything anyway. 7.1 will have a working one. There must be something else wrong though, normally the patch should just be ignored. You will probably experience other problems even if you skip it. Again, make sure your error reporting level reports warnings and notices if you want more clues of what could be going on.
There is definitely no database restoration needed, the patch is just not doing anything besides causing a fatal error.