Launcher crashes in console.warn() with Qt.Test import

Launching this app with launcher:

import QtQuick 2.4
import Ubuntu.Test 1.0

UbuntuTestCase {
    function test_something() {
        console.warn("hello");
    }
}

will dump core, like this:

tim@ubuntu:~/dev/ubuntu-ui-toolkit/m/35-tstHeaderActions/tests/unit/tst_components$ ../../launcher/launcher tst_header_sections.qml
ASSERT: "QTest::TestLoggers::loggerCount() != 0" in file qtestlog.cpp, line 274
Aborted (core dumped)

Note that you don't have to call console.warn() directly, but it may be called by changing a parameter for testing. The original test (tst_header_sections.qml) crashes because it has this function:

    function test_warn_when_too_many_sections() {
        ignoreWarning("It is not recommended or supported to use more than three sections in Page.head.sections.model.")
        page.head.sections.model = ["1", "2", "3", "4"];
    }

which crashes because PageHeadSections currently has this warning printed:

    onModelChanged: {
        if (model && model.length > 3) {
            console.warn("It is not recommended or supported to use more than three sections in Page.head.sections.model.");
        }
    }