Do filesort if handler has the HA_NOT_READ_PREFIX_LAST flag set.

mysys/my_symlink.c

@@ -115,11 +115,15 @@ int my_realpath(char *to, const char *filename, myf MyFlags)
       (!lstat(filename,&stat_buff) && S_ISLNK(stat_buff.st_mode)))
   {
     char *ptr;
+    DBUG_PRINT("info",("executing realpath"));
     if ((ptr=realpath(filename,buff)))
+    {
       strmake(to,ptr,FN_REFLEN-1);
+    }
     else
     {
       /* Realpath didn't work;  Use original name */
+      DBUG_PRINT("error",("realpath failed with errno: %d", errno));
       my_errno=errno;
       if (MyFlags & MY_WME)
 	my_error(EE_REALPATH, MYF(0), filename, my_errno);

sql/sql_select.cc

@@ -5577,7 +5577,7 @@ test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,ha_rows select_limit,
 	    with key part (A) and then traverse the index backwards.
 	  */
 	  if (table->file->table_flags() & HA_NOT_READ_PREFIX_LAST)
-	    DBUG_RETURN(1);
+	    DBUG_RETURN(0);			// Use filesort
 	  tab->read_first_record=       join_read_last_key;
 	  tab->read_record.read_record= join_read_prev_same;
 	  /* fall through */