Description of problem:
When editing JenkinsPipeline BC,its finished builds configurations are also changed, this is wrong

Version-Release number of selected component (if applicable):
openshift v1.3.0-alpha.3+d8c9694
kubernetes v1.3.0+507d3a7
etcd 2.3.0+git

How reproducible:
Always

Steps to Reproduce:
1. Create JenkinsPipeline BC and trigger builds
$ oc create -f https://raw.githubusercontent.com/openshift/origin/master/examples/image-streams/image-streams-centos7.json -n openshift
$ oc create -f https://raw.githubusercontent.com/openshift/origin/master/examples/jenkins/jenkins-ephemeral-template.json
$ oc new-app -f https://raw.githubusercontent.com/openshift/origin/master/examples/jenkins/pipeline/samplepipeline.json
$ oc new-app jenkins-ephemeral
$ oc start-build sample-pipeline 
2. When sample-pipeline #1 is finished, access BC edit page at /edit/pipelines/sample-pipeline, change the Jenkinsfile content, such as add stage 'test'
node('maven') {
stage 'build'
.....
stage 'test'
echo "this is test"
.....
}

3. Click "Save' on BC edit page
4. Check BC 'sample-pipeline' page about Jenkinsfile content
5. Check build sample-pipeline #1 page about Jenkinsfile content

Actual results:
4. On BC 'sample-pipeline' page, Jenkinsfile is shown with new changes
node('maven') {
stage 'build'
.....
stage 'test'
echo "this is test"
.....
}
5. For finished sample-pipeline #1 build, Jenkinsfile content is also shown with new changes
node('maven') {
stage 'build'
.....
stage 'test'
echo "this is test"
.....
}

Expected results:
5. Editing BC should not change its finished builds configurations

Additional info:
CLI could show correct Jenkinsfile about build sample-pipeline #1
# oc get builds sample-pipeline #1 -o yaml
node('maven') {
stage 'build'
...
state 'deploy'
..
}