vim-patch:8.2.4741: startup test fails

Problem:    Startup test fails.
Solution:   Avoid an error for verbose expansion.  Fix that the "0verbose"
            command modifier doesn't work.
60895f3e36

Most code changes has already been ported.

runtime/syntax/synload.vim

@@ -30,7 +30,7 @@ fun! s:SynSet()
     unlet b:current_syntax
   endif
 
-  let s = expand("<amatch>")
+  0verbose let s = expand("<amatch>")
   if s == "ON"
     " :set syntax=ON
     if &filetype == ""