patch 8.2.2202: write file test still fails on MS-Windows

Problem:    Write file test still fails on MS-Windows.
Solution:   Set fileformat with the :edit command
diff --git a/src/testdir/test_writefile.vim b/src/testdir/test_writefile.vim
index 92f19ce..07beb64 100644
--- a/src/testdir/test_writefile.vim
+++ b/src/testdir/test_writefile.vim
@@ -682,8 +682,8 @@
   call assert_equal(0z6E6F656F6C, readfile('XNoEolSetEol', 'B'))
 
   " when file is read 'eol' is off
-  set ff=unix nofixeol
-  e! XNoEolSetEol
+  set nofixeol
+  e! ++ff=unix XNoEolSetEol
   call assert_equal(0, &eol)
 
   " writing with 'eol' set adds the newline