origin: flake: build failed, blob upload unknown

https://openshift-gce-devel.appspot.com/build/origin-ci-test/logs/test_branch_origin_extended_conformance_gce/1876/

2017-11-04T23:34:05.243653000Z  ---> Running in 298138ef4692
2017-11-04T23:34:05.317400000Z  ---> e1f92cbcad87
2017-11-04T23:34:05.323456000Z Removing intermediate container 298138ef4692
2017-11-04T23:34:05.325477000Z Successfully built e1f92cbcad87
2017-11-04T23:34:05.336059000Z Pushing image docker-registry.default.svc:5000/extended-test-docker-build-pullsecret-f6zg5-r48qs/image1:latest ...
2017-11-04T23:34:06.517339000Z Pushed 0/1 layers, 3% complete
2017-11-04T23:34:36.782828000Z Pushed 0/1 layers, 100% complete
2017-11-04T23:34:42.398258000Z Pushed 1/1 layers, 100% complete
2017-11-04T23:34:56.162252000Z Registry server Address: 
2017-11-04T23:34:56.162577000Z Registry server User Name: serviceaccount
2017-11-04T23:34:56.162824000Z Registry server Email: serviceaccount@example.org
2017-11-04T23:34:56.163070000Z Registry server Password: <<non-empty>>
2017-11-04T23:34:56.163316000Z error: build error: Failed to push image: blob upload unknown