Bad call flags in PyCFunction_Call

When trying to execute qwt tests on python3 I get a SystemError Exception:

Traceback (most recent call last):
  File "/usr/local/lib/python3.4/dist-packages/qwt/tests/BodeDemo.py", line 298, in <module>
    demo = make()
  File "/usr/local/lib/python3.4/dist-packages/qwt/tests/BodeDemo.py", line 285, in make
    demo = BodeDemo()
  File "/usr/local/lib/python3.4/dist-packages/qwt/tests/BodeDemo.py", line 205, in __init__
    self.plot = BodePlot(self)
  File "/usr/local/lib/python3.4/dist-packages/qwt/tests/BodeDemo.py", line 77, in __init__
    QwtPlot.__init__(self, *args)
  File "/usr/local/lib/python3.4/dist-packages/qwt/plot.py", line 335, in __init__
    self.initAxesData()
  File "/usr/local/lib/python3.4/dist-packages/qwt/plot.py", line 395, in initAxesData
    d.scaleWidget.setTransformation(d.scaleEngine.transformation())
  File "/usr/local/lib/python3.4/dist-packages/qwt/scale_widget.py", line 724, in setTransformation
    self.layoutScale()
  File "/usr/local/lib/python3.4/dist-packages/qwt/scale_widget.py", line 470, in layoutScale
    bd0, bd1 = self.getBorderDistHint()
  File "/usr/local/lib/python3.4/dist-packages/qwt/scale_widget.py", line 656, in getBorderDistHint
    start, end = self.__data.scaleDraw.getBorderDistHint(self.font())
  File "/usr/local/lib/python3.4/dist-packages/qwt/scale_draw.py", line 577, in getBorderDistHint
    s = -self.labelRect(font, minTick).top()
  File "/usr/local/lib/python3.4/dist-packages/qwt/scale_draw.py", line 999, in labelRect
    lbl = self.tickLabel(font, value)
  File "/usr/local/lib/python3.4/dist-packages/qwt/scale_draw.py", line 419, in tickLabel
    lbl.textSize(font)
  File "/usr/local/lib/python3.4/dist-packages/qwt/text.py", line 937, in textSize
    ) = self.__data.textEngine.textMargins(font)
  File "/usr/local/lib/python3.4/dist-packages/qwt/text.py", line 302, in textMargins
    top = fm.ascent() - self.effectiveAscent(font)
  File "/usr/local/lib/python3.4/dist-packages/qwt/text.py", line 261, in effectiveAscent
    return ASCENTCACHE.setdefault(fontKey, self.findAscent(font))
  File "/usr/local/lib/python3.4/dist-packages/qwt/text.py", line 281, in findAscent
    line = img.scanLine(row).asstring(linebytes)
SystemError: Bad call flags in PyCFunction_Call. METH_OLDARGS is no longer supported!

My installed versions: Python '3.4.3 (default, Oct 14 2015, 20:28:29) \n[GCC 4.8.4]' numpy 1.8.2 qwt 0.5.5 PyQt4 4.8.6 (* This is the one loaded by guidata) PyQt5 5.2.1 Cython 0.20.1post0 guidata 1.7.5 guiqwt 3.0.2

PlotPyStack / PythonQwt

Bad call flags in PyCFunction_Call #40