[Phpmyadmin-devel] Any special reason that "require" but not "require _once" on libraries/common.inc.php

[adam]

Hi all,

I make pull request about adding Unit test case for  libraries/ServerStatusData.class.php
https://github.com/phpmyadmin/phpmyadmin/pull/394

but a build error if I don't change the "require" to "require _once" on libraries/common.inc.php 
https://travis-ci.org/phpmyadmin/phpmyadmin/jobs/7221724

it is:
Fatal error: Cannot redeclare class PMA_Error_Handler in /home/travis/build/phpmyadmin/phpmyadmin/libraries/Error_Handler.class.php on line 20


I want to know that Any special reason that "require" but not "require _once" on libraries/common.inc.php


thanks,
Adam