QtQuick Compiler compiled javascript file in extension plugin is not found

Without QtQuick Compiler, if javascript file like MyUtils.js is defined in qmldir like this:

MyUtils 1.0 MyUtils.js

It can be used in QML like this:

import CustomModule 1.0
...
MyUtils.somefunction()

However, if Qt Quick Compiler is used (and qmldir file does not have entry for it), it cannot be found. There is a workaround by adding this to qmldir:

MyUtils 1.0 qrc:/MyUtils.js