Workaround assumptions in trigger-ci-job-config.

This patch pushes a simple change such that the repository returns
a HEAD~1. This is a workaround for an assumption made in:
  * ci/tf-ci-scripts.git/tree/trigger-ci-job-configs.yaml#n87
and present in other scripts.

Change-Id: I33f5609a8a5e209ac9ea34cb68e572f8a0d6bc9b
1 file changed
tree: b67d5cc6a40e8213ebf3b0f71ee37b69e3dc30b9
  1. hafnium-build-test-review.yaml
  2. view.yaml