/includes/modules/payment/paypal.php: What's this code supposed to do?

In v1.5.1, the instantiation function for the paypal class (in /includes/modules/payment/paypal.php) reads:

Code:

---

  function paypal($paypal_ipn_id = '') {
    global $order, $messageStack;
    $this->code = 'paypal';
    $this->codeVersion = '1.5.1';
    if (IS_ADMIN_FLAG === true) {
      // Payment Module title in Admin
      $this->title = STORE_COUNTRY != '223' ? MODULE_PAYMENT_PAYPAL_TEXT_ADMIN_TITLE_NONUSA : MODULE_PAYMENT_PAYPAL_TEXT_ADMIN_TITLE;
      if (IS_ADMIN_FLAG === true && defined('MODULE_PAYMENT_PAYPAL_IPN_DEBUG') && MODULE_PAYMENT_PAYPAL_IPN_DEBUG != 'Off') $this->title .= '<span class="alert"> (debug mode active)</span>';
      if (IS_ADMIN_FLAG === true && MODULE_PAYMENT_PAYPAL_TESTING == 'Test') $this->title .= '<span class="alert"> (dev/test mode active)</span>';
    } else {
      $this->title = MODULE_PAYMENT_PAYPAL_TEXT_CATALOG_TITLE; // Payment Module title in Catalog
    }
    $this->description = MODULE_PAYMENT_PAYPAL_TEXT_DESCRIPTION;
    $this->sort_order = MODULE_PAYMENT_PAYPAL_SORT_ORDER;
    $this->enabled = ((MODULE_PAYMENT_PAYPAL_STATUS == 'True') ? true : false);
    if ((int)MODULE_PAYMENT_PAYPAL_ORDER_STATUS_ID > 0) {
      $this->order_status = MODULE_PAYMENT_PAYPAL_ORDER_STATUS_ID;
    }
    if (is_object($order)) $this->update_status();
    $this->form_action_url = 'https://' . MODULE_PAYMENT_PAYPAL_HANDLER;

  if (PROJECT_VERSION_MAJOR != '1' && substr(PROJECT_VERSION_MINOR, 0, 3) != '5.0') $this->enabled = false;

    // verify table structure
    if (IS_ADMIN_FLAG === true) $this->tableCheckup();
  }

---

What's the purpose of the line that I've colored red? If it's meant to cause the payment module to work only on the version of Zen Cart with which it's released, it's probably a good thing that the clause is flawed because no one would ever have paypal active on v1.5.1!

If the clause is meant to limit the module's function only to a specific Zen Cart version, it should be written as

Code:

---

if (PROJECT_VERSION_MAJOR != '1' || substr(PROJECT_VERSION_MINOR, 0, 3) != '5.0') $this->enabled = false;

---

Oh, and for v1.5.1 the last comparison would probably want to be changed, too.

If that's not what the clause is meant for, please fill in my blanks.

Note: Similar clauses exist in both the paypaldp and paypalwpp modules, with different minor version comparison values ...