Fix pep8 issue with net functional tests cleanup

The previous patch lacked a blank line and due to jenkins
giving false positives I missed the problem.

Change-Id: I6f64d06f2827278cb91ddb3f87904ce5593c45c2
Signed-off-by: Antoni S. Puimedon <asegurap@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/16561
Reviewed-by: Dan Kenigsberg <danken@redhat.com>