OpenShift 4 image-registry operator degraded with "unsupported protocol scheme" error

Issue

• The image-registry operator degrades with the following error when S3 bucket object storage is used.

$ oc get clusteroperator
NAME                       VERSION   AVAILABLE   PROGRESSING   DEGRADED   SINCE   MESSAGE
image-registry             4.8.32    True        True          False      69d     Progressing: Unable to apply resources: unable to sync storage configuration: RequestError: send request failed Progressing: caused by: Head "test-s3.example.com/ocp-image-bucket": unsupported protocol scheme "