QImage constructor never frees his memory

QImage(data,size1,size2,format) contructor seem to occupy memory, but put in combination wil PIL.Image.tostring() this memory is never freed.

I put the constructor in a loop and found the following:
if data is always the same, there is no increase in memory, if data != data(t+1), then it increases really fast.

Please take a look at the code in attachement, containing these situations, and all the code needed to reproduce the bug (reproduced on 2 different computers).

ps: I posted the issue on stackoverflow, here: http://stackoverflow.com/questions/14716850/pil-to-qimage-conversion-qimage-constructor-does-not-free-memory