QProgressBar.resize() works only for vertical bars, clips horizontal

[captain_hindsight]

I'm using PyQt5 to make a widget which has dynamically-placed and resized progressbars on top of an image. The problem is, QProgressBar.resize() works fine for vertical progressbars, and clips horizontal ones. In particular, it doesn't produce a square at all if asked to.

I've been on that issue for hours now, there is no way I'm solving this one on my own it seems. I've got a much bigger code, but I reproduced the problem with the following:

@class Test(QWidget):
def init(self):
super(Test, self).init()
self.pb = QProgressBar(self);
self.pb.show()

def upd(self):
    self.pb.resize(50,50)

gui = Test()
gui.show()
gui.upd()@

This does not produce a square. What is happening?

Here is what it looks like on the main program:
!http://i.stack.imgur.com/Y2rHZ.png(Problem on main program)!