When testing EZP-28868 for AdminUI (ez Platform v2) with eZ Design Engine we've discovered that it's definitely too easy to break back-office, because app/Resources/views is hard-coded as the first directory of _override templates.

This use case is too common to be ignored, so what we need is to drop _override feature at least for app/Resources/views directory. It might be still valid to keep allowing using this feature by means of ezdesign.templates_override_paths configuration key. Reasoning is that if a Developer explicitly uses override feature of eZ Design, then he knows what he's doing.

The other discussed approach is to completely remove _override feature, but that might be too much.