[BUG] [KafkaChannel] error retrieving webhook: mutatingwebhookconfigurations.admissionregistration.k8s.io \"webhook.kafka.eventing.knative.dev\" not found

[grebois]

Expected Behavior

Kafka webhook should work as expected

Actual Behavior

Kafka webhook crashes with:

$ kubectl logs kafka-webhook-7b7776f4d5-2gx8j -n knative-eventing
{"level":"info","ts":"2019-11-01T08:23:18.178Z","caller":"logging/config.go:108","msg":"Successfully created the logger.","knative.dev/jsonconfig":"{\n  \"level\": \"info\",\n  \"development\": false,\n  \"outputPaths\": [\"stdout\"],\n  \"errorOutputPaths\": [\"stderr\"],\n  \"encoding\": \"json\",\n  \"encoderConfig\": {\n    \"timeKey\": \"ts\",\n    \"levelKey\": \"level\",\n    \"nameKey\": \"logger\",\n    \"callerKey\": \"caller\",\n    \"messageKey\": \"msg\",\n    \"stacktraceKey\": \"stacktrace\",\n    \"lineEnding\": \"\",\n    \"levelEncoder\": \"\",\n    \"timeEncoder\": \"iso8601\",\n    \"durationEncoder\": \"\",\n    \"callerEncoder\": \"\"\n  }\n}\n"}
{"level":"info","ts":"2019-11-01T08:23:18.178Z","caller":"logging/config.go:109","msg":"Logging level set to info"}
{"level":"info","ts":"2019-11-01T08:23:18.178Z","caller":"logging/config.go:76","msg":"Fetch GitHub commit ID from kodata failed: open /var/run/ko/HEAD: no such file or directory"}
{"level":"info","ts":"2019-11-01T08:23:18.178Z","logger":"kafka-webhook","caller":"webhook/main.go:79","msg":"Starting the Kafka Messaging Webhook","knative.dev/controller":"kafka-webhook"}
{"level":"info","ts":"2019-11-01T08:23:18.192Z","logger":"kafka-webhook","caller":"webhook/webhook.go:162","msg":"Found certificates for webhook...","knative.dev/controller":"kafka-webhook"}
{"level":"error","ts":"2019-11-01T08:23:18.197Z","logger":"kafka-webhook","caller":"webhook/webhook.go:179","msg":"failed to register webhook","knative.dev/controller":"kafka-webhook","error":"error retrieving webhook: mutatingwebhookconfigurations.admissionregistration.k8s.io \"webhook.kafka.eventing.knative.dev\" not found","stacktrace":"knative.dev/eventing-contrib/vendor/knative.dev/pkg/webhook.(*Webhook).Run.func1\n\t/home/prow/go/src/knative.dev/eventing-contrib/vendor/knative.dev/pkg/webhook/webhook.go:179\nknative.dev/eventing-contrib/vendor/golang.org/x/sync/errgroup.(*Group).Go.func1\n\t/home/prow/go/src/knative.dev/eventing-contrib/vendor/golang.org/x/sync/errgroup/errgroup.go:57"}
{"level":"error","ts":"2019-11-01T08:23:18.198Z","logger":"kafka-webhook","caller":"webhook/main.go:147","msg":"controller.Run() failed","knative.dev/controller":"kafka-webhook","error":"webhook server bootstrap failed <nil>","stacktrace":"main.main\n\t/home/prow/go/src/knative.dev/eventing-contrib/kafka/channel/cmd/webhook/main.go:147\nruntime.main\n\t/usr/local/go/src/runtime/proc.go:200"}
{"level":"info","ts":"2019-11-01T08:23:18.198Z","logger":"kafka-webhook","caller":"webhook/main.go:149","msg":"Kafka webhook stopping","knative.dev/controller":"kafka-webhook"}

Steps to Reproduce the Problem

1.Create an empty cluster v1.14.7-gke.14
2.Deploy Istio 1.3.3 and Knative 0.10.0
3.Apply https://github.com/knative/eventing-contrib/releases/download/v0.10.0/kafka-channel.yaml
4. Follow https://github.com/knative/eventing-contrib/blob/master/kafka/channel/README.md

Additional Info

Works perfectly on Knative 0.9.0 and KafkaChannel 0.9.0

$ kubectl api-versions | grep admissionregistration.k8s.io/v1beta1
admissionregistration.k8s.io/v1beta1