Xtrabackup 1.9 beta makes a full backup when streaming and and incremental flags are set

When making an incremental backup using Innobackupex, I used the following command:

innobackupex --incremental /disk2/backups/incremental/ --extra-lsndir=/disk2/backups/lsn2/ --stream=tar --incremental-basedir=/disk2/backups/lsn/2012-02-08_17-47-09/ | gzip --fast > incremental_beta.tar.gz

However, when looking at the output, it seemed xtrabackup was being passed incorrect parameters:

xtrabackup --backup --suspend-at-end --log-stream --target-dir=./ --extra-lsndir='/disk2/backups/lsn2/' --incremental-basedir='/disk2/backups/lsn/2012-02-08_17-47-09/'

and it was clear based on how long the 'backup' was taking and the sized of the streamed file that this was a full snapshot not a delta