poweroff-log-attach and reboot-log-attach job will fail

[Po-Hsu Lin]

These two job will fail, the log files could be found in CHECKBOX_DATA directory, but they're not compressed into a .gz file.
I think that's why these two jobs failed.

How to reproduce:
Select the following jobs to run:
fwts_wakealarm
poweroff
poweroff-log-attach
reboot
reboot-log-attach

Log files from the io-logs directory:
$ cat 2013.com.canonical.certification__power-management_poweroff-log-attach.stdout
/home/ubuntu/.cache/plainbox/sessions/pbox-n0xp7va7.session/CHECKBOX_DATA/pm_test.poweroff.1.log
$ cat 2013.com.canonical.certification__power-management_poweroff-log-attach.stderr
tar: Removing leading `/' from member names
cat: /home/ubuntu/.cache/plainbox/sessions/pbox-n0xp7va7.session/CHECKBOX_DATA/power-management_poweroff.tgz: No such file or directory
$ cat 2013.com.canonical.certification__power-management_reboot-log-attach.stdout
/home/ubuntu/.cache/plainbox/sessions/pbox-n0xp7va7.session/CHECKBOX_DATA/pm_test.reboot.1.log
$ cat 2013.com.canonical.certification__power-management_reboot-log-attach.stderr
tar: Removing leading `/' from member names
cat: /home/ubuntu/.cache/plainbox/sessions/pbox-n0xp7va7.session/CHECKBOX_DATA/power-management_reboot.tgz: No such file or directory

And I am curious why we use 'cat' to cat a tgz file?
(from the job file)
command: tar cvfz power-management_poweroff.tgz $PLAINBOX_SESSION_SHARE/*poweroff.1.log && cat $PLAINBOX_SESSION_SHARE/power-management_poweroff.tgz