Improve vim colors plugin

vim/plugin/colors.vim

@@ -17,9 +17,14 @@ augroup END
 
 if $TERM=="xterm-kitty"
 	augroup kitty
+		call system("which updatecolors")
+		if v:shell_error
 			let s:kitty_bg=system("kitty @ get-colors | grep ^background")
 			let g:kitty_bg=s:kitty_bg[match(s:kitty_bg, "#"):]
 			au VimLeavePre * echom system("kitty @ set-colors background=".g:kitty_bg)
+		else
+			au VimLeavePre * call system("updatecolors")
+		end
 	augroup END
 end