Method cache_clear_all() in memcache.db.inc doesn't clear memcache if $cid is set and $wildcard is TRUE

I'm using the book module in my Drupal 6 installation and one of the features is the ability to re-order the pages within a book. The page re-ordering is done by adjusting the weights of the menu item links which come under the book root node's menu item. When saving the adjusted order on my memcache.db.inc-enabled site I get a success message yet the page ordering shown on the results page looks unchanged.

Digging deeper the culprit lies in here inside cache_clear_all() in memcache.db.inc:

    if ($wildcard) {
      dmemcache_flush($table);
      if ($cid == '*') {
        db_query("TRUNCATE TABLE {". $table ."}");
      }
      else {
        db_query("DELETE FROM {". $table ."} WHERE cid LIKE '%s%%'", $cid);
      }
    }

As we can see if $wildcard is TRUE but $cid is not '*' then only the database cache data is deleted; the Memcache data is unchanged. This is incorrect behaviour.

We can't perform a LIKE query against Memcache so the available options are:

1. Fetch the actual key names from the database using a SELECT LIKE query and then delete each of these entries from Memcache.
2. Flush the memcache entries for the given table even if $cid is not '*'.

I've opted for option 2 since it simpler to implement and moreover, can be applied as a solution to the pure-Memcaching cacheing solution too.