Improve guard so it works for no eof new line

autoload/cargo/quickfix.vim

@@ -1,4 +1,5 @@
 if !exists('g:polyglot_disabled') || index(g:polyglot_disabled, 'rust') == -1
+
 function! cargo#quickfix#CmdPre() abort
     if &filetype ==# 'rust' && get(b:, 'current_compiler', '') ==# 'cargo'
         " Preserve the current directory, and 'lcd' to the nearest Cargo file.
@@ -25,4 +26,5 @@ function! cargo#quickfix#CmdPost() abort
 endfunction
 
 " vim: set et sw=4 sts=4 ts=8:
+
 endif