anchor.diff:  the build that is created uses the `*immutableid*` resolved from the
   `*ImageStream*` referenced by the `*Strategy*`. This ensures that builds
   are performed using consistent image tags for ease of reproduction.
  +
  +[NOTE]
  +====
  +Image streams that point to Docker images in v1 Docker registries will only trigger a build
  +once when the image stream tag becomes available and not on subsequent image updates. This is due
  +to the lack of uniquely identifiable images in v1 Docker registries.
  +====
   
   [#using-docker-credentials-for-pushing-and-pulling-images]
   == Using Docker Credentials for Pushing and Pulling Images
  
positive.code: In this case, the `*sourceStrategy*` definition is consuming the `latest` tag of
  the image stream named `ruby-20-centos7` located within this namespace.
  
  . Define an image change trigger:
  +
  ====
  
  ----
  {
    "type": "imageChange",
    "imageChange": {}
  }
  ----
  ====
  +
  This defines an image change trigger that monitors the `*ImageStream*` and
  `*Tag*` as defined by the strategy's `*from*` field. When a change occurs, a new
  build is triggered and is supplied with an immutable Docker tag that points to
  the new image that was just created. This new image will be used by the strategy
  when it executes for the build. For example, the resulting build will be:
  +
  ====
  
  ----
  
negative.code: `_<system-registry>_` is defined as a service with the name `docker-registry`
  running in OpenShift.
  
  . If an image stream is the base image for the build, set the from field in the
  build strategy to point to the image stream:
  +
  ====
  
  