Qt 5 renders pixel garbage with some PCF fonts

Some PCF fonts are rendered with pixel garbage around them by Qt 5. Qt 4 does not show this problem.

Here's a simple test program that should demonstrate the bug:

#include <QApplication>
#include <QTextEdit>

int main(int argc, char* argv[])
{
    QApplication a(argc, argv);
    QTextEdit tedit("The quick brown fox jumps over the lazy dog");
    tedit.setFont(QFont("Fixed [Sony]", 20));
    tedit.show();
    return a.exec();
}

The "font-sony-misc" font is provided by X.Org and should be available by default in most Linux distros. Some other PCF fonts also trigger the problem, like "Clean" and "Console".

I'm attaching a screenshot that shows the problem.