assert in font database search for Symbol

This code assert with the message 'ASSERT failure in void QtFontFamily::ensurePopulated(): "Bangla Sangam MN", file text/qfontdatabase.cpp, line 413'

    QFontDatabase database;
    m_excludedFonts = database.families(QFontDatabase::Symbol);

This asserts did appear after I upgraded to MacOSX El Capitan with Xcode 7.2.. Before that the same code worked fine. It works fine on MacOSX but not on iOS.