Checkbox Test: memory/memory_stress_ng Miss on arm64

When running canonical-certification-server memory_stress_ng has failures but indicates it has passed.

Running stress-ng lockbus stressor for 300 seconds....
stress-ng: unrecognized option '--lockbus'
Try 'stress-ng --help' for more information.
return_code is 1
*****************************************************************
** Error 1 reported on stressor lockbus!)
*****************************************************************

...

stress-ng: info: [35248] unsuccessful run completed in 300.02s (5 mins, 0.02 secs)
return_code is 2
*****************************************************************
** Error 2 reported on stressor vm-rw!)
*****************************************************************

...

return_code is 0
*******************************************************************
** stress-ng memory test failed; most recent error was 0
*******************************************************************

# uname -a
Linux ubuntu 4.4.0-15-generic #31-Ubuntu SMP Fri Mar 18 19:13:00 UTC 2016 aarch64 aarch64 aarch64 GNU/Linux
root@ubuntu:/home/ubuntu/.cache/plainbox/sessions/pbox-s31gyyp4.session/io-logs# cat /etc/issue
Ubuntu Xenial Xerus (development branch) \n \l

sudo apt-cache policy stress-ng
stress-ng:
  Installed: 0.05.23-1
  Candidate: 0.05.23-1
  Version table:
 *** 0.05.23-1 500
        500 http://us.ports.ubuntu.com/ubuntu-ports xenial/universe arm64 Packages
        100 /var/lib/dpkg/status
     0.05.12-1ppa1 500
        500 http://ppa.launchpad.net/hardware-certification/public/ubuntu xenial/main arm64 Packages

sudo apt-cache policy canonical-certification-server
canonical-certification-server:
  Installed: 0.23-1
  Candidate: 0.23-1
  Version table:
 *** 0.23-1 500
        500 http://ppa.launchpad.net/hardware-certification/public/ubuntu xenial/main arm64 Packages
        100 /var/lib/dpkg/status