patch 7.4.1837

Problem:    The BufUnload event is triggered twice, when :bunload is used with
             set to  or .
Solution:   Do not trigger the event when ml_mfp is NULL. (Hirohito Higashi)

src/buffer.c

@@ -574,9 +574,12 @@ buf_freeall(buf_T *buf, int flags)
     int		is_curbuf = (buf == curbuf);
 
     buf->b_closing = TRUE;
+    if (buf->b_ml.ml_mfp != NULL)
+    {
 	apply_autocmds(EVENT_BUFUNLOAD, buf->b_fname, buf->b_fname, FALSE, buf);
 	if (!buf_valid(buf))	    /* autocommands may delete the buffer */
 	    return;
+    }
     if ((flags & BFA_DEL) && buf->b_p_bl)
     {
 	apply_autocmds(EVENT_BUFDELETE, buf->b_fname, buf->b_fname, FALSE, buf);

src/testdir/test_autocmd.vim

@@ -7,10 +7,7 @@ func Test_vim_did_enter()
   " becomes one.
 endfunc
 
-if !has('timers')
-  finish
-endif
-
+if has('timers')
   func ExitInsertMode(id)
     call feedkeys("\<Esc>")
   endfunc
@@ -33,3 +30,33 @@ func Test_cursorhold_insert_ctrl_x()
     call feedkeys("a\<C-X>", 'x!')
     call assert_equal(0, g:triggered)
   endfunc
+endif
+
+function Test_bufunload()
+  augroup test_bufunload_group
+    autocmd!
+    autocmd BufUnload * call add(s:li, "bufunload")
+    autocmd BufDelete * call add(s:li, "bufdelete")
+    autocmd BufWipeout * call add(s:li, "bufwipeout")
+  augroup END
+
+  let s:li=[]
+  new
+  setlocal bufhidden=
+  bunload
+  call assert_equal(["bufunload", "bufdelete"], s:li)
+
+  let s:li=[]
+  new
+  setlocal bufhidden=delete
+  bunload
+  call assert_equal(["bufunload", "bufdelete"], s:li)
+
+  let s:li=[]
+  new
+  setlocal bufhidden=unload
+  bwipeout
+  call assert_equal(["bufunload", "bufdelete", "bufwipeout"], s:li)
+
+  augroup! test_bufunload_group
+endfunc

src/version.c

@@ -753,6 +753,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1837,
 /**/
     1836,
 /**/