anchor.diff:  +
   ----
   $ kn service list hello
  -
   No services found.
   ----
  
positive.code: +
  ----
  $ kn service update hello --env TARGET=Kn
  
  Waiting for service 'hello' to become ready ... OK
  Service 'hello' updated in namespace 'default'.
  ----
  +
  The service's environment variable `TARGET` is now set to `Kn`.
  
negative.code: +
  ----
  $ kn service create hello --image gcr.io/knative-samples/helloworld-go --env TARGET=Knative
  Creating service 'hello' in namespace 'default':
  
    0.085s The Route is still working to reflect the latest desired specification.
    0.101s Configuration "hello" is waiting for a Revision to become ready.
   11.590s ...
   11.650s Ingress has not yet been reconciled.
   11.726s Ready to serve.
  
  Service 'hello' created with latest revision 'hello-gsdks-1' and URL:
  http://hello.default.apps-crc.testing
  ----
  
  