Description of problem:

Setup ocp 4.0 cluster, login web console, and navigate to 'Operator Hub', select etcd-operator, in page "Create Operator Subscription", check 'singlenamespace-alpha' option in 'Update Channel' and check 'A specific namespace on the cluster' in 'Installation Mode', select a customer's namespace, such as:'ocp-test-boss', Currently, the button 'Subscribe' is blue and could be clicked, click 'Subscribe', the operation will succeed, the etcd-operator will be created successfull in the specified namespace. but if you haven't clicked the button 'Subscribe' right now, and after 5-10 seconds, the web page prompt msg: "Namespace does not support install modes for this Operator." and button 'Subscribe' will be grey.


Cluster version is 4.0.0-0.nightly-2019-03-28-030453
console commit: 7cddd5b3b4f1ba6b4f4e17993f6f00ed6b17dcbc

How reproducible:
Always

Steps to Reproduce:
As description
Actual results:
As title.
Expected results:
There is not unexpected msg prompts.