I4a9f3d9b3ac7afe989c0efb1fa4e7fd792cd9610 ("IP Conntrack Manager changes
for FWaaS v2") moved several constants into neutron.common.constants
and neutron.agent.linux.ip_conntrack modules. This broke fullstack test
l3agent classes that relied on the old import path. This patch restores
the removed constants in the original places (referring to the new
location). This hopefully fixes fullstack l3 agent tests.
Change-Id: I976b74698d631f6ec809b15470ff9ea3f9fbf7be
Closes-Bug: #1694772