Restore: convert mal-formed PRTs from a fatal error to a warning.

backup/moodle2/restore_qtype_stack_plugin.class.php

@@ -295,20 +295,16 @@ class restore_qtype_stack_plugin extends restore_qtype_plugin {
             $graph->layout();
             $roots = $graph->get_roots();
             if (count($roots) != 1 || $graph->get_broken_cycles()) {
-                $questions = $DB->get_records('question', array('id' => $prt->questionid), '', 'name');
-                $qnames = array();
-                foreach ($questions as $q) {
-                    $qnames[] = $q->name;
-                }
+                $question = $DB->get_record('question', array('id' => $prt->questionid));
                 if (count($roots) != 1) {
                     $err = 'abnormal root count: '.count($roots).'(<>1)';
                 } else {
                     $err = 'broken cycles: '.implode('.', $graph->get_broken_cycles());
                 }
-                throw new coding_exception('The PRT named "' . $prt->name .
+                $this->step->log('The PRT named "' . $prt->name .
                         '" is malformed in question id ' . $prt->questionid .
-                        ', question named "' . implode(', ', $qnames) .
-                        '".  Error reported: ' . $err);
+                        ', question named "' . $question->name .
+                        '".  Error reported: ' . $err, backup::LOG_WARNING);
             }
             reset($roots);
             $firstnode = key($roots) - 1;