qisys.command: fix dead lock in Process.run()

Happened when terminate() failed but the process.communicate() call
was still running.

Change-Id: I3bc001a503ccba8905142cac38bca6366d3d4490
Reviewed-on: http://gerrit.aldebaran.lan:8080/15013
Tested-by: gerrit
Reviewed-by: hcuche <hcuche@aldebaran-robotics.com>
Reviewed-by: proullon <proullon@aldebaran-robotics.com>