Description of problem:
User can modify Build spec.source.type:Git and it can be saved.

Version-Release number of selected component (if applicable):
openshift v3.3.1.3
kubernetes v1.3.0+52492b4

How reproducible:
1.Create a new project；
2.oc new-app https://raw.githubusercontent.com/openshift-qe/v3-testfiles/master/image/language-image-templates/php-56-rhel7-stibuild.json
3.From web console to try to modify bc "php-sample-build",click action->Edit Yaml to modify like the following:
spec:
..............
source:
    git123:
      uri: https://github.com/wzheng1/php-example-app
    type: Git123
4.Click Save



Actual results:

php-sample-build was updated. Infomation in BC is like:
source:
    type: None


Expected results:
BuildConfig  "php-sample-build" is invalid: spec.source.type:  Invalid value: "Git123".

Additional info:
The same with use of  "oc edit bc".