Warning: PDO::quote() expects parameter 1 to be string, array given in dpq()

Problem/Motivation

In branch 7.x-1.x, calling dpq() with arguments that are arrays results in:

Warning: PDO::quote() expects parameter 1 to be string, array given in dpq()

Proposed resolution

  function dpq($query, $return = FALSE, $name = NULL) {
    ...
    foreach ((array) $query->arguments() as $key => $val) {
-     $quoted[$key] = $connection->quote($val);
+     if (is_array($val)) {
+       $quoted[$key] = implode(', ', array_map(function($v) use ($connection) { return $connection->quote($v); }, $val));
+     }
+     else {
+       $quoted[$key] = $connection->quote($val);
+     }
    }
    ...
}