Indexing Not Working also with 4.7.3

I upgraded from 4.6 to 4.7.1 (using MySQL 5.0.19) and could not successfully perform search. ReIndexing and rerunning the cron didn't help .. Following are the changes I made to get the new version working.

a) Actually the cron job would end in a CGI /Fast CGi crash for some reason or after the cron finished there would be messages in watchdog indicating "foreach ($node->taxonomy as $term) {" in "taxonomy_node_update_index". For some reason "$node->taxonomy" was not an array; placing an "if" condition before the "For" loop solved this.

function taxonomy_node_update_index(&$node) {
  $output = array();
  if ($node->taxonomy) {    //*IP Added the "If" check
    foreach ($node->taxonomy as $term) {
        $output[] = $term->name;
    }
  }
  if (count($output)) {
    return '<strong>('. implode(', ', $output) .')</strong>';
  }
}

b) Still the cron jobs would never update the "%" of complete indices. In "node_update_index()" "$last" is extracted from "variable_get('node_cron_last', 0)" .. this should actually be "$last_changed" as following:

$last_change = variable_get('node_cron_last', 0);        //*IP+1 changed $last->$last_change
$last = $last_change;

Next the SQL query does a "GREATEST" operation which will return a NULL value if either of the values are null (this is true as of MySQL version 5.0.13). So I changed the query to return "n.changed" value as well and later inside the "while" loop I used that value. The SQl query also had an extra "$last" argument being passed.

 $result = db_query_range('SELECT GREATEST(c.last_comment_timestamp, n.changed) as last_change, n.changed as nodeChanged, n.nid FROM {node} n LEFT JOIN {node_comment_statistics} c ON n.nid = c.nid WHERE n.status = 1 AND ((GREATEST(n.changed, c.last_comment_timestamp) = %d AND n.nid > %d) OR (n.changed > %d OR c.last_comment_timestamp > %d)) ORDER BY GREATEST(n.changed, c.last_comment_timestamp) ASC, n.nid ASC', $last, $last_nid, $last, $last, 0, $limit);
  //*IP-1 removed an extra $last in the above statement and returning n.changed
 
  while ($node = db_fetch_object($result)) {
    if (!$node->last_change) {      //*IP+2 Check to handle NULL value from GREATEST operation
        $node->last_change = $node->nodeChanged;
    }

  $last_change = $node->last_change;

Since "$last_change" is getting set from "$node->last_change" so a NULL value would cause that to become NULL which would cause nothing to be saved in "node_update_shutdown". As a result of this the indexing was always "0%" and so every cron run would just index the first 100 nodes over and over again.