patch 8.2.3384: cannot disable modeline for an individual file

Problem:    Cannot disable modeline for an individual file.
Solution:   Recognize "nomodeline" in a modeline. (Hu Jialun, closes #8798)
diff --git a/src/testdir/test_modeline.vim b/src/testdir/test_modeline.vim
index 19c99b5..f28ad3e 100644
--- a/src/testdir/test_modeline.vim
+++ b/src/testdir/test_modeline.vim
@@ -360,4 +360,12 @@
   bw
 endfunc
 
+func Test_modeline_disable()
+  set modeline
+  call writefile(['vim: sw=2', 'vim: nomodeline', 'vim: sw=3'], 'Xmodeline_disable')
+  edit Xmodeline_disable
+  call assert_equal(2, &sw)
+  call delete('Xmodeline_disable')
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab