Typo in grade/lib.php causes incorrect sorting

The following source (from HEAD as of 9/25/2008) contains a typo in line 105 where 'sortfield1' should be 'sortfield2':

102 $ofields = ", u.$this->sortfield1 AS usrt1";
103 $order = "usrt1 $this->sortorder1";
104 if (!empty($this->sortfield2))

{ 105 $ofields .= ", u.$this->sortfield1 AS usrt2"; 106 $order .= ", usrt2 $this->sortorder2"; 107 }

The SQL generated by this typo-affected code tries to sort by $this->sortfield1 twice and neglects $this->sortfield2. We didn't notice the problem until one of our instructors encountered it while exporting his gradebook.

This is a one-character fix.

Thanks,
Philip Cali and Adam Zapletal