Console-cyrillic just calls "kbd_mode -u". This command alone produces the bug.
The bug is easy to reproduce: do not install console-cyrillic, but simply add the kbd_mode -u command to /etc/rc.local.
On the GDM login screen press Alt+F2, and you will switch to text console!
So, the but is related to kdb, not to console-cyrillic.
Console-cyrillic just calls "kbd_mode -u". This command alone produces the bug.
The bug is easy to reproduce: do not install console-cyrillic, but simply add the kbd_mode -u command to /etc/rc.local.
On the GDM login screen press Alt+F2, and you will switch to text console!
So, the but is related to kdb, not to console-cyrillic.