CVE-2016-1906: Authorization bypass in Openshift

The vulnerability stems from missing update operation handling in the build strategy admission controller. The GitHub fix (openshift/origin#6576) shows the admission handler was modified to include 'admission.Update' in its operations. The original code only checked 'admission.Create', allowing unauthorized strategy changes via updates. The test cases in 'test/integration/build_admission_test.go' confirm this by adding update validation checks. Both the handler registration (NewBuildByStrategy) and admission logic (Admit) were deficient in handling updates, making them the root cause.