patch 8.2.4452: test for what 8.2.4436 fixes does not check for regression

Problem:    Test for what 8.2.4436 fixes does not check for regression.
Solution:   Set several options. (Ken Takata, closes #9830)
diff --git a/src/testdir/test_vartabs.vim b/src/testdir/test_vartabs.vim
index 74b07ba..e15a072 100644
--- a/src/testdir/test_vartabs.vim
+++ b/src/testdir/test_vartabs.vim
@@ -446,11 +446,12 @@
   let save_encoding = &encoding
   new
   set encoding=iso8859-1
-  silent exe "norm :se \<C-A>\<C-C>"
+  set compatible linebreak list revins smarttab
   set vartabstop=400
   exe "norm i00\t\<C-D>"
   bwipe!
   let &encoding = save_encoding
+  set nocompatible linebreak& list& revins& smarttab& vartabstop&
 endfunc