When changing the encoding (++enc) during operation, the iskeyword setting flies, how to fix it?

Question

vim

A menu for selecting the encoding for displaying a file has been formed:

set wildmenu
set wcm=<TAB>
menu Encoding.windows-1251 :e ++enc=cp1251<CR>
menu Encoding.cp866 :e ++enc=cp866<CR>
menu Encoding.koi8-r :e ++enc=koi8-r<CR>
menu Encoding.utf-8 :e ++enc=utf-8<CR>
map <F8> :emenu Encoding.<TAB>

When you select an encoding, the iskeyword setting flies.
How to bypass it?