fix flaky test
fix flaky test

Previously spun up two jobs which each slept for 1 second. It would link to
the first one, and link to the second after that in serial. This would fail
because they would both exit after 1 second, not just the first one.

cloudfoundry-incubator/garden,tangfeixiong/garden,cloudfoundry-incubator/garden-linux,shashidharatd/garden-linux,shashidharatd/garden-linux,shashidharatd/garden-linux,savaki/garden,savaki/garden,cloudfoundry-incubator/garden,tsaleh/garden,tsaleh/garden,cloudfoundry-incubator/garden-linux,tangfeixiong/garden,shashidharatd/garden-linux,cloudfoundry-incubator/garden-linux