Fix flakey unit test in opensuse_net_manager_test
Fix flakey unit test in opensuse_net_manager_test

[#146464235](https://www.pivotaltracker.com/story/show/146464235)

cloudfoundry/bosh-agent,gu-bin/bosh-agent,gu-bin/bosh-agent,mattcui/bosh-agent,cloudfoundry/bosh-agent,mattcui/bosh-agent,gu-bin/bosh-agent,mattcui/bosh-agent