osd_disk_activate: Use python binary variable
osd_disk_activate: Use python binary variable

07abbbe has been merged without being rebase with 778c7f9 changes.
This mades 07abbbe non python 3 compatible.

Signed-off-by: Dimitri Savineau <a50a620e679eed14f4e99998b821cea8884cf228@redhat.com>

ceph/ceph-docker,ceph/ceph-docker