patch 9.1.0158: 'shortmess' "F" flag doesn't work properly with 'autoread'

Problem:  'shortmess' "F" flag doesn't work properly with 'autoread'
          (after 9.1.0154)
Solution: Hide the file info message instead of the warning dialog
          (zeertzjq)

closes: #14159
closes: #14158

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_options.vim b/src/testdir/test_options.vim
index fa65f5c..fbfbaae 100644
--- a/src/testdir/test_options.vim
+++ b/src/testdir/test_options.vim
@@ -1294,23 +1294,41 @@
 endfunc
 
 func Test_shortmess_F3()
-  defer delete('X_dummy')
+  call writefile(['foo'], 'X_dummy', 'D')
 
   set hidden
   set autoread
   e X_dummy
-  e file
-
+  e Xotherfile
+  call assert_equal(['foo'], getbufline('X_dummy', 1, '$'))
   set shortmess+=F
-  call writefile(["foo"], 'X_dummy')
-  call assert_true(empty(execute('bn', '')))
-  call assert_true(empty(execute('bn', '')))
+  echo ''
+
+  if has('nanotime')
+    sleep 10m
+  else
+    sleep 2
+  endif
+  call writefile(['bar'], 'X_dummy')
+  bprev
+  call assert_equal('', Screenline(&lines))
+  call assert_equal(['bar'], getbufline('X_dummy', 1, '$'))
+
+  if has('nanotime')
+    sleep 10m
+  else
+    sleep 2
+  endif
+  call writefile(['baz'], 'X_dummy')
+  checktime
+  call assert_equal('', Screenline(&lines))
+  call assert_equal(['baz'], getbufline('X_dummy', 1, '$'))
 
   set shortmess&
   set autoread&
   set hidden&
-  bwipe
-  bwipe
+  bwipe X_dummy
+  bwipe Xotherfile
 endfunc
 
 func Test_local_scrolloff()