This is a regression from 5.8.0 beta. Running the controls 2 gallery example causes crash on startup with the error:

W Gallery : (null):0 ((null)): QQmlApplicationEngine failed to load component
W Gallery : (null):0 ((null)): qrc:/gallery.qml:224 Type Dialog unavailable
W Gallery : file:///data/user/0/org.qtproject.example.gallery/qt-reserved-files/qml/QtQuick/Controls.2/Dialog.qml:76 Type DialogButtonBox unavailable
W Gallery : file:///data/user/0/org.qtproject.example.gallery/qt-reserved-files/qml/QtQuick/Controls.2/qmldir:-1 plugin cannot be loaded for module ".data.user.0.org.qtproject.example.gallery.qt-reserved-files.qml.QtQuick.Controls": Module namespace 'QtQuick.Controls' does not match import URI '.data.user.0.org.qtproject.example.gallery.qt-reserved-files.qml.QtQuick.Controls'

Confirmed on Android 7 (Nexus 9 and Pixel C) and Android 6 (Galaxy S7)

The example works on Android 4.4.4 (Nexus 10)