Comment 2 for bug 1200282

xtrabackup_checkpoints file is not updated after it is once written on
the donor; from_lsn sure but to_lsn won't be the same after the joiner
server starts (joiner or any receiver of this incremental backup). Hence
providing this to_lsn will result in a failed incremental prepare.

Currently, the lsn needs to be manually obtained like:
        lsn=$(/pxc/bin/mysqld --defaults-file=$WSREP_SST_OPT_CONF --basedir=/pxc --wsrep-recover 2>&1 | grep -o 'log sequence number .*' | cut -d " " -f 4 | head -1)

        (or something equivalent)

and xtrabackup_checkpoints file's to_lsn needs to be manually
obtained with lsn obtained from previous step.

So, if instead lsn can be directly provided to
innobackupex/xtrabackup it would be better.

(It would also be better if xtrabackup can directly get the lsn,
but that is outside the scope of this bug)