vim-patch:8.2.0639: MS-Windows: messages test still fails

Problem:    MS-Windows: messages test still fails.
Solution:   Filter out the maintainer message.
49b2fb36ca

src/nvim/testdir/test_messages.vim

@@ -1,20 +1,16 @@
 " Tests for :messages, :echomsg, :echoerr
 
-function Test_messages()
+source shared.vim
+
+func Test_messages()
   let oldmore = &more
   try
     set nomore
-    " Avoid the "message maintainer" line.
-    let $LANG = ''
-    let $LC_ALL = ''
-    let $LC_MESSAGES = ''
-    let $LC_COLLATE = ''
 
     let arr = map(range(10), '"hello" . v:val')
     for s in arr
       echomsg s | redraw
     endfor
-    let result = ''
 
     " get last two messages
     redir => result
@@ -25,22 +21,17 @@ function Test_messages()
 
     " clear messages without last one
     1messages clear
-    redir => result
-    redraw | messages
-    redir END
-    let msg_list = split(result, "\n")
+    let msg_list = GetMessages()
     call assert_equal(['hello9'], msg_list)
 
     " clear all messages
     messages clear
-    redir => result
-    redraw | messages
-    redir END
-    call assert_equal('', result)
+    let msg_list = GetMessages()
+    call assert_equal([], msg_list)
   finally
     let &more = oldmore
   endtry
-endfunction
+endfunc
 
  " Patch 7.4.1696 defined the "clearmode()" command for clearing the mode
 " indicator (e.g., "-- INSERT --") when ":stopinsert" is invoked.  Message