Comment 8 for bug 225055

I fixed the problem manualy by adding in the /etc/X11/xorg.conf
In the InputDevice Section

Option "XkbLayout" "us,gr" #The layouts that you want to use.
Option "XkbOptions" "grp:alt_shift_toggle" #this is for changing the layout by pressing Alt+Shift

Now it looks like

Section "InputDevice"
 Identifier "Generic Keyboard"
 Driver "kbd"
 Option "CoreKeyboard"
 Option "XkbRules" "xorg"
 Option "XkbModel" "pc105"
 Option "XkbLayout" "us,gr"
 Option "XkbOptions" "grp:alt_shift_toggle"
EndSection

and it was

Section "InputDevice"
 Identifier "Generic Keyboard"
 Driver "kbd"
 Option "CoreKeyboard"
 Option "XkbRules" "xorg"
 Option "XkbModel" "pc105"
 Option "XkbLayout" "us"
EndSection

now when i reboot my system the keyboard layout changes flawless.

This is just a workaround but the bug sustains i suppose
for new installation so it must be fixed.