standby, pg_basebackup and last xlog file

  Hello!

  I wrote to general (  [GENERAL] standby, pg_basebackup and last xlog file ) some times ago. but still hasn't got any feedback.

  Hello!

  Is there any reason why pg_basebackup has limitation in an online backup from the standby: "The backup history file is not created in the database cluster backed up." ?

  So i can't get last xlog file needed to restore :(

  Think i can use -x option for getting last xlog file, but i would like to minimize size of resulting backup. // i also get all WALs by archive_command, so there is no reason to get two copies of each wal during basebackup.

  Also maybe i can use something like ( pg_last_xlog_replay_location() + 1 ) after pg_basebackup finished.

  Does anybody know true way to getting last xlog file in case of applying pg_basebackup to standby?
  How pg_basebackup gets last xlog file in case of standby and -x option?