Output Image Labels is not overwritten in OCP 3.6

Issue

• Output Image Labels is not overwritten in OCP 3.6

1. oc new-app centos/ruby-22-centos7~https://github.com/openshift/ruby-ex.git

2. oc describe image sha256:ffdc3ef7ab48d38dea314b4a97ed1e56188112166557fc509920a76ebd2411c2 | grep "io.openshift.build.commit.message"
        io.openshift.build.commit.message=Merge pull request #18 from durandom/master

3. oc edit bc/ruby-ex
  output:
    imageLabels:
    - name: io.openshift.build.commit.message
      value: registry.mycompany.com
    to:
      kind: ImageStreamTag
      name: ruby-ex:latest

4. oc start-build ruby-ex

5. oc describe image sha256:ec095b52875956380cb4b9cc5ab0ff0c693a038da534398ac44ceafa30d9b72f | grep "io.openshift.build.commit.message"
        io.openshift.build.commit.message=Merge pull request #18 from durandom/master <--- (expected : registry.mycompany.com)