Comment 2 for bug 1051466

StacktraceTop:
 BacklightHelper::brightness (this=0x1226b20, args=...) at ../../../powerdevil/daemon/backends/upower/backlighthelper.cpp:191
 qt_static_metacall (_a=0x7fff747940a0, _o=<optimized out>, _c=<optimized out>, _id=<optimized out>) at moc_backlighthelper.cpp:52
 BacklightHelper::qt_static_metacall (_o=_o@entry=0x1226b20, _c=_c@entry=QMetaObject::InvokeMetaMethod, _id=_id@entry=0, _a=_a@entry=0x7fff747940a0) at moc_backlighthelper.cpp:46
 QMetaMethod::invoke (this=this@entry=0x7fff74794210, object=object@entry=0x1226b20, connectionType=connectionType@entry=Qt::DirectConnection, returnValue=..., val0=..., val1=..., val2=..., val3=..., val4=..., val5=..., val6=..., val7=..., val8=..., val9=...) at kernel/qmetaobject.cpp:1664
 QMetaObject::invokeMethod (obj=0x1226b20, member=<optimized out>, type=Qt::DirectConnection, ret=..., val0=..., val1=..., val2=..., val3=..., val4=..., val5=..., val6=..., val7=..., val8=..., val9=...) at kernel/qmetaobject.cpp:1179