[Feature:DeploymentConfig] deploymentconfigs when run iteratively [Conformance] should only deploy the last deployment

[bparees]

/tmp/openshift/build-rpm-release/tito/rpmbuild-originaSQW3g/BUILD/origin-3.7.0/_output/local/go/src/github.com/openshift/origin/test/extended/deployments/deployments.go:142
Expected error:
    <*errors.errorString | 0xc4215922d0>: {
        s: "found multiple running deployments: [deployment-simple-1 deployment-simple-2]",
    }
    found multiple running deployments: [deployment-simple-1 deployment-simple-2]
not to have occurred
/tmp/openshift/build-rpm-release/tito/rpmbuild-originaSQW3g/BUILD/origin-3.7.0/_output/local/go/src/github.com/openshift/origin/test/extended/deployments/deployments.go:131

https://openshift-gce-devel.appspot.com/build/origin-ci-test/pr-logs/pull/16924/test_pull_request_origin_extended_conformance_gce/9899/

[bparees]

@mfojtik seeing this one a lot.

[bparees]

https://openshift-gce-devel.appspot.com/build/origin-ci-test/pr-logs/pull/16925/test_pull_request_origin_extended_conformance_gce/9905/

[tnozicka]

dupe of #16870
but I'll keep it open for now so people can easily find it