trailing equal ("=") character added to a transformed path

I wanted to secure a soap request, so when a client request the wsdl file, here is the path :
http://mydomain.com/services/myservice?wsdl
The securepages_get_query() function transformed it in
https://mydomain.com/services/myservice?wsdl=

It's just a minor code adjustment to remove the trailing "=" when theres only a key but no value

function securepages_get_query($query) {
  unset($query['q']);
  $q = array();

  foreach ($query as $key => $value) {
    if (is_array($value)) {
      $value = http_build_query(array($key => $value));
    }
	$encoded_key = securepages_urlencode($key);
	$encoded_value = securepages_urlencode($value);
	$str = $encoded_key;
	if ($encoded_value != "") {
		$str .= '='.$encoded_value;
	}
    $q[] = $str;
  }

  return implode('&', $q);
}