Some keymap files in the package "kbd" have *.gz extension, but they are not compressed.

$ file -i $(find /usr/share/kbd/keymaps/ -name "*.gz")|grep "text/plain"
/usr/share/kbd/keymaps/i386/qwerty/ruwin_cplk-UTF-8.map.gz:     text/plain; charset=us-ascii
/usr/share/kbd/keymaps/i386/qwerty/ru4.map.gz:                  text/plain; charset=us-ascii
/usr/share/kbd/keymaps/i386/qwerty/ruwin_alt-CP1251.map.gz:     text/plain; charset=us-ascii

So these keymaps cannot be used.

$ loadkeys ru4
Loading /usr/share/kbd/keymaps/i386/qwerty/ru4.map.gz

gzip: /usr/share/kbd/keymaps/i386/qwerty/ru4.map.gz: not in gzip format