tst_qgraphicseffect fails on qpa, xcb

Information of screen 346:
  width.........: 1920
  height........: 1200
  depth.........: 24
  white pixel...: ffffff
  black pixel...: 0

Running window manager: KWin
********* Start testing of tst_QGraphicsEffect *********
Config: Using QTest library 5.0.0, Qt 5.0.0
PASS   : tst_QGraphicsEffect::initTestCase()
PASS   : tst_QGraphicsEffect::setEnabled()
PASS   : tst_QGraphicsEffect::source()
PASS   : tst_QGraphicsEffect::boundingRectFor()
PASS   : tst_QGraphicsEffect::boundingRect()
PASS   : tst_QGraphicsEffect::boundingRect2()
created regular window: 56623106
PASS   : tst_QGraphicsEffect::draw()
created regular window: 56623110
PASS   : tst_QGraphicsEffect::opacity()
PASS   : tst_QGraphicsEffect::grayscale()
PASS   : tst_QGraphicsEffect::colorize()
created regular window: 56623114
PASS   : tst_QGraphicsEffect::drawPixmapItem()
created regular window: 56623118
PASS   : tst_QGraphicsEffect::deviceCoordinateTranslateCaching()
created regular window: 56623122
PASS   : tst_QGraphicsEffect::inheritOpacity()
PASS   : tst_QGraphicsEffect::dropShadowClipping()
created regular window: 56623126
FAIL!  : tst_QGraphicsEffect::childrenVisibilityShouldInvalidateCache() Compared values are not the same
   Actual (parent.nbPaint): 2
   Expected (1): 1
   Loc: [tst_qgraphicseffect.cpp(691)]
created regular window: 56623130
FAIL!  : tst_QGraphicsEffect::prepareGeometryChangeInvalidateCache() Compared values are not the same
   Actual (item->nbPaint): 3
   Expected (1): 1
   Loc: [tst_qgraphicseffect.cpp(719)]
created regular window: 56623134
FAIL!  : tst_QGraphicsEffect::itemHasNoContents() Compared values are not the same
   Actual (child->nbPaint): 3
   Expected (1): 1
   Loc: [tst_qgraphicseffect.cpp(750)]
PASS   : tst_QGraphicsEffect::cleanupTestCase()
Totals: 15 passed, 3 failed, 0 skipped
********* Finished testing of tst_QGraphicsEffect *********