[ticket/13113] Updates the base url only when the front-end isn't app.php

PHPBB3-13113
Merge pull request #3001 from Nicofuma/ticket/13113

[ticket/13113] Updates the base url only when the front-end isn't app.php
Merge branch 'develop-ascraeus' into develop

* develop-ascraeus:
  [ticket/13113] Updates the base url only when the front-end isn't app.php