test_caret.py crashes on Travis with this stack:
?? () from /usr/lib/x86_64-linux-gnu/dri/swrast_dri.so
?? () from /usr/lib/x86_64-linux-gnu/dri/swrast_dri.so
?? () from /usr/lib/x86_64-linux-gnu/dri/swrast_dri.so
QSGBatchRenderer::Renderer::renderBatches() () from .../site-packages/PyQt5/Qt/lib/libQt5Quick.so.5
QSGBatchRenderer::Renderer::render() () from .../site-packages/PyQt5/Qt/lib/libQt5Quick.so.5
QSGRenderer::renderScene(QSGBindable const&) () from .../site-packages/PyQt5/Qt/lib/libQt5Quick.so.5
QSGRenderer::renderScene(unsigned int) () from .../site-packages/PyQt5/Qt/lib/libQt5Quick.so.5
QSGDefaultRenderContext::renderNextFrame(QSGRenderer*, unsigned int) () from .../site-packages/PyQt5/Qt/lib/libQt5Quick.so.5
QQuickWindowPrivate::renderSceneGraph(QSize const&) () from .../site-packages/PyQt5/Qt/lib/libQt5Quick.so.5
QQuickRenderControl::render() () from .../site-packages/PyQt5/Qt/lib/libQt5Quick.so.5
?? () from .../site-packages/PyQt5/Qt/lib/libQt5QuickWidgets.so.5
?? () from .../site-packages/PyQt5/Qt/lib/libQt5QuickWidgets.so.5
QObject::event(QEvent*) () from .../site-packages/PyQt5/Qt/lib/libQt5Core.so.5
QWidget::event(QEvent*) () from .../site-packages/PyQt5/Qt/lib/libQt5Widgets.so.5
QQuickWidget::event(QEvent*) () from .../site-packages/PyQt5/Qt/lib/libQt5QuickWidgets.so.5
?? () from .../site-packages/PyQt5/Qt/lib/libQt5WebEngineWidgets.so.5
QApplicationPrivate::notify_helper(QObject*, QEvent*) () from .../site-packages/PyQt5/Qt/lib/libQt5Widgets.so.5
QApplication::notify(QObject*, QEvent*) () from .../site-packages/PyQt5/Qt/lib/libQt5Widgets.so.5
sipQApplication::notify(QObject*, QEvent*) () from .../site-packages/PyQt5/QtWidgets.so
QCoreApplication::notifyInternal2(QObject*, QEvent*) () from .../site-packages/PyQt5/Qt/lib/libQt5Core.so.5
QTimerInfoList::activateTimers() () from .../site-packages/PyQt5/Qt/lib/libQt5Core.so.5
?? () from .../site-packages/PyQt5/Qt/lib/libQt5Core.so.5
g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from .../site-packages/PyQt5/Qt/lib/libQt5Core.so.5
QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from .../site-packages/PyQt5/Qt/lib/libQt5Core.so.5
SQL is included in the Archlinux pyqt5 package, but not in Debian.
We need this so the debian-based CI builds will pass with the new
sql-based completion implementation.