It seems Motorola is skipping Android 5.0 entirely for the DROID Turbo, leap frogging all the way to Android 5.1. This decision wasn't motivated so much because of buggy Android 5.0 code, as much as it was 5.1's native support for VoLTE. From Phandroid - Motorola Droid Turbo will skip Android 5.0 and jump directly to Android 5.1 for its VoLTE support