Some time glGetBooleanv(GL_STEREO) returns FALSE in Qt5

With Qt5, After setting stereo to TRUE in the QSurfaceFormat, glGetBooleanv( GL_STEREO, ... ) returns FALSE when it should return TRUE.
This works with Qt4.

This seems depending up on the gfx, The bug appears on NVIDIA Quadro cards (tested with K4000 and M6000), but
everything works fine with an AMD Firepro W8000.

Attached are 2 versions of a minimal program:

• "main_qt4.cpp" is written for Qt4 and works properly.
• "main_qt5.cpp" is the exact same program written for Qt5 and shows the bug.