A patch that fixes this has been submitted for the next week integration. See the linked PULL request for details.

Nice ... so I have to wait until next week. Thanks!

I re-triaged this today and set the fix version to 2.1 instead of 2.0.3 for the following reasons:

• The proper solution of this requires non-trivial changes in the code (introducing a new lang installer instead of fixing the same pattern at several places). That is too much the stable branch and must go to master
• The bug is not critical at all. Note that if the admin selects just "de_kids" to be installed, de_du is installed automatically and there is a warning automatically displayed that "de" is missing. Having to install parent languages manually had been de-facto standard in Moodle for a long time.

PULL-571 created for Moodle 2.1. Deutsch admins should be warned that they should not choose de_kids as a language of the installation of the new 2.0 servers (not considered as a big problem as the missing language pack is easily spottable after the installation). From 2.1, it will work correctly though.

INSTRUCTIONS FOR TESTING (difficulty: moderate, requires controlled installation and upgrade, requires using CLI utilities)

1. For each of the three installer types (install.php, admin/cli/install.php, admin/cli/install_database.php) try to install a fresh new Moodle from integration.git, using "Deutsch - Kids (de_kids)" as the language (note there is no need to actually install Moodle - you can stop at the moment where the lang packs are downloaded)
2. TEST: make sure that in all cases, moodledata/lang/ contains all three de_kids, de_du and de packs
3. Install a fresh new Moodle from integration.git, using the English language
4. Go to Site administration > Language > Language packs
5. Select "Deutsch - Kids (de_kids)" and install it
6. TEST: make sure that de_kids is installed, de_du is installed (as a parent) and de is installed, too (as a parent of de_du)

Good work, thanks David

When does this work in stable Moodle 2.0?

The version Moodle 2.0.2+ (20110406) still has the problem and does not load Deutsch (de) when I delete all german packages and try to install only Deutsch - Kids (de_kids). Moodle automaticly loads Deutsch - du (de_du) but not the main package.

Ralf

Or does it work only in Moodle 2.1?

Yes Ralf, this was fixed for Moodle 2.1 and is not planned to be backported. See my previous comment. Note that admins are at least warned that the main lang pack is missing.

Hi David, yes it works with Moodle 2.1dev. I installed it today into my Moodle4Mac. Thanks!