patch 9.1.0154: shm=F not respected when reloading buffer with 'autoread'

Problem:  shm=F not respected when reloading buffer with 'autoread'
Solution: Check SHM_FILEINFO in buf_check_timestamp()
          (Shougo Matsushita)

closes: #14144

Signed-off-by: Shougo Matsushita <Shougo.Matsu@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/fileio.c

@@ -4294,7 +4294,7 @@ buf_check_timestamp(
 #endif
     }
 
-    if (mesg != NULL)
+    if (mesg != NULL && !shortmess(SHM_FILEINFO))
     {
 	path = home_replace_save(buf, buf->b_fname);
 	if (path != NULL)

src/testdir/test_options.vim

@@ -1293,6 +1293,26 @@ func Test_shortmess_F2()
   call assert_fails('call test_getvalue("abc")', 'E475:')
 endfunc
 
+func Test_shortmess_F3()
+  defer delete('X_dummy')
+
+  set hidden
+  set autoread
+  e X_dummy
+  e file
+
+  set shortmess+=F
+  call writefile(["foo"], 'X_dummy')
+  call assert_true(empty(execute('bn', '')))
+  call assert_true(empty(execute('bn', '')))
+
+  set shortmess&
+  set autoread&
+  set hidden&
+  bwipe
+  bwipe
+endfunc
+
 func Test_local_scrolloff()
   set so=5
   set siso=7

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    154,
 /**/
     153,
 /**/