updated for version 7.4.251
Problem:    Crash when BufAdd autocommand wipes out the buffer.
Solution:   Check for buffer to still be valid. Postpone freeing the buffer
            structure. (Hirohito Higashi)
diff --git a/src/fileio.c b/src/fileio.c
index 17f36e7..f8b384b 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -9548,13 +9548,19 @@
 
     /*
      * When stopping to execute autocommands, restore the search patterns and
-     * the redo buffer.
+     * the redo buffer.  Free buffers in the au_pending_free_buf list.
      */
     if (!autocmd_busy)
     {
 	restore_search_patterns();
 	restoreRedobuff();
 	did_filetype = FALSE;
+	while (au_pending_free_buf != NULL)
+	{
+	    buf_T *b = au_pending_free_buf->b_next;
+	    vim_free(au_pending_free_buf);
+	    au_pending_free_buf = b;
+	}
     }
 
     /*