MDL-30466 Backup: Fixed duplicate completion record check error

backup/moodle2/restore_stepslib.php

@@ -2237,8 +2237,6 @@ protected function process_availability($data) {
  *  - Activity includes completion info (file_exists)
  */
 class restore_userscompletion_structure_step extends restore_structure_step {
-    private $done = array();
-
     /**
      * To conditionally decide if this step must be executed
      * Note the "settings" conditions are evaluated in the
@@ -2282,15 +2280,14 @@ protected function process_completion($data) {
         $data->userid = $this->get_mappingid('user', $data->userid);
         $data->timemodified = $this->apply_date_offset($data->timemodified);
 
+        // Find the existing record
+        $existing = $DB->get_record('course_modules_completion', array(
+                'coursemoduleid' => $data->coursemoduleid,
+                'userid' => $data->userid), 'id, timemodified');
         // Check we didn't already insert one for this cmid and userid
         // (there aren't supposed to be duplicates in that field, but
         // it was possible until MDL-28021 was fixed).
-        $key = $data->coursemoduleid . ',' . $data->userid;
-        if (array_key_exists($key, $this->done)) {
-            // Find the existing record
-            $existing = $DB->get_record('course_modules_completion', array(
-                    'coursemoduleid' => $data->coursemoduleid,
-                    'userid' => $data->userid), 'id, timemodified');
+        if ($existing) {
             // Update it to these new values, but only if the time is newer
             if ($existing->timemodified < $data->timemodified) {
                 $data->id = $existing->id;
@@ -2299,16 +2296,13 @@ protected function process_completion($data) {
         } else {
             // Normal entry where it doesn't exist already
             $DB->insert_record('course_modules_completion', $data);
-            // Remember this entry
-            $this->done[$key] = true;
         }
     }
 
     protected function after_execute() {
         // This gets called once per activity (according to my testing).
         // Clearing the array isn't strictly required, but avoids using
         // unnecessary memory.
-        $this->done = array();
     }
 }