Pecan: remove deprecation warning
Pecan: remove deprecation warning

Addresses the warning below:

DeprecationWarning: BaseException.message has been deprecated as of Python 2.6

Change-Id: I1aaebb28c3c9ca2ede9e900428fb5c7eef6d29e6
Closes-bug: #1582522

openstack/neutron,igor-toga/local-snat,openstack/neutron,mahak/neutron,igor-toga/local-snat,mahak/neutron,bigswitch/neutron,eayunstack/neutron,cloudbase/neutron,bigswitch/neutron,sebrandon1/neutron,huntxu/neutron,mahak/neutron,openstack/neutron,eayunstack/neutron,noironetworks/neutron,sebrandon1/neutron,huntxu/neutron,cloudbase/neutron,noironetworks/neutron