Drupal 8 changes installer language to take from GET langcode

The change is going to land in #1260716: Improve language onboarding user experience hopefully soon.

Damien Tournoud and @webchick suggested we put in a little 3-line compatibility layer in the patch to keep it work with the locale argument until we fix the testing system and the testbot rollouts of it. They suggested we get the patch land like this and make the testbots align later. This is documented on the original issue via an IRC log.

I'm not intricately familiar with the testing system, so I don't know if the installation of the system is entirely in the realm of simpletest, in which case, we could have fixed it in the same commit I guess, or if it is a d.o issue. Damien and Angie seemed to believe d.o changes are required.

I think the only remaining question is why we have no new tests with the patch, one you also asked on the issue and I've replied there. So where should we move this issue?

No, all is changed in D8 is that the language is taken from 'langcode' in GET not 'locale'. The committed patch has these 5 lines so it still passes tests:

+  // @todo: remove this testbot compatibility layer once the testbot is fixed.
+  if (isset($_GET['locale'])) {
+    $install_state['parameters']['langcode'] = $_GET['locale'];
+  }
+

Until we fix the testing system on d.o, Drupal 8 needs to carry these five lines. Obviously we don't want Drupal 8 to be released with these 5 lines. The discussion of this 5 line compatibility layer is in the IRC thread pasted at http://drupal.org/node/1260716#comment-5226480.

If we just remove the compatibility layer, PIFT respondes with this: http://qa.drupal.org/pifr/test/191604 Quoting:

Installing: failed to arrive at database configuration page using install path http://drupaltestbot664-mysql/checkout/install.php?profile=standard&locale=en

Obviously the test system wants to avoid looking at the profile selector or language selector form. Since the GET argument name changed in D8, we need to change the testing system to pass langcode=en instead of locale=en, that is it. Depending on how you handle compatibility with testing for D6, D7 and D8, you might want to do 'locale=en&langcode=en' instead, the extra langcode should not bother D6/D7, the extra locale should not bother D8.

I hope this helps clean it up :)

How can I help move this forward?

The upgrade tests run with an imported DB copy, so no, they do not run install.php. I've checked quickly and could not find a reference to locale in those tests.

All right #1426954: Remove locale backward compatibility layer in installer submitted for the testbot! Thanks for rolling this out!