setData for QQmlComponent handles uncorrectly "import" path

Hello,
This is my first bug submit, sorry if something is wrong or incomplete.

Trying to load a component using the setData call for QQmlComponent fails, when the data contains an include to a further directory. (Even if not used)

    QtQuick2ApplicationViewer viewer;
    viewer.setMainQmlFile(QStringLiteral("qml/main.qml"));
    viewer.showExpanded();

    QQmlContext *context = new QQmlContext(viewer.rootContext());
    QQmlComponent component(viewer.engine());
    component.setData( "import QtQuick 2.0;import \"Boxes\";Rectangle { width: 100; height: 62;}",QUrl("qml/"));

This generates an ASSERT

ASSERT: "!url.isRelative() && (QQmlFile::urlToLocalFileOrQrc(url).isEmpty() || !QDir::isRelativePath(QQmlFile::urlToLocalFileOrQrc(url)))" 

in file qml\qqmltypeloader.cpp, line 1665

Url value before the assert in getQmlDir is "://qml/Boxes/qmldir"

Am I doing something wrong? Is it normal that the "qmldir" string gets added to the url from QQmlTypeLoader::Blob::addImport?
I tried various QUrl, without success.

Thanks and regards,
Christophe