QUrl.toLocalFile returns nothing if given non-canonical path

Using some PyQt4 code to demonstrate:

python -c "from PyQt4 import QtCore; print 'File: %s' % QtCore.QUrl('foo.txt').toLocalFile()"

Against Qt 4.7.x, this function returns:

File: foo.txt

Using Qt 4.8.0-rc1, this function outputs:

File:

We noticed the impact affecting KDE's KUrl class, and that all audio system notifications configured that reference media files like "KDE-K3B-Finish-Success.ogg" now fail (whereas "/usr/share/sounds/KDE-K3B-Finish-Success.ogg" works).