patch 8.1.1379: filechanged test hangs

Problem:    Filechanged test hangs.
Solution:   Do not check 'autoread'.

src/fileio.c

@@ -6774,9 +6774,8 @@ buf_check_timestamp(
 	// FileChangedShell autocmd)
 	if (stat_res < 0)
 	{
-	    // When 'autoread' is set we'll check the file again to see if it
-	    // re-appears.
-	    buf->b_mtime = (buf->b_p_ar >= 0 ? buf->b_p_ar : p_ar);
+	    // Check the file again later to see if it re-appears.
+	    buf->b_mtime = -1;
 	    buf->b_orig_size = 0;
 	    buf->b_orig_mode = 0;
 	}

src/testdir/test_filechanged.vim

@@ -115,8 +115,9 @@ func Test_file_changed_dialog()
   call assert_match('E211:', v:warningmsg)
   call assert_equal(2, line('$'))
   call assert_equal('extra line', getline(2))
+  let v:warningmsg = 'empty'
 
-  " Recreate buffer and reload
+  " change buffer, recreate the file and reload
   call setline(1, 'buffer is changed')
   silent !echo 'new line' >Xchanged_d
   call feedkeys('L', 'L')

src/version.c

@@ -767,6 +767,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1379,
 /**/
     1378,
 /**/