[REG 5.2->5.3] QPrinter::{width,height} return incorrect size

When you print with a dpi setting different from the dpi setting of the default printer, QPrinter::width() and height() return values as if the dpi setting of the default printer was used.

tl;dr:
1. start attached program (with Qt 5.3 or higher)
2. press print
3. change dpi to a higher value or select another printer with a different dpi setting
4. QPrinter::pageRect(QPrinter::DevicePixel) and QPaintDevice::width() and height() should return the same size, which they don't

I attached a small test program which demonstrates this issue.
In my case my default printer is set to 600dpi.
In the print preview the returned size is 4958x7017.
If I print without changing anything the size stays the same.
But when I change the dpi setting in the print dialog or select another printer with a different dpi setting (The dpi setting has to be different from the default dpi setting that was active after starting the program) the size still returns 4958x7017 while pageRect(QPrinter::DevicePixel) returns 9917x14033.