Watch a git repo and only rebuild if there are changes.

gistfile1.yml

my_repo:
  git.latest:
    - name: https://github.com/some/repo.git
    - rev: develop
    - target: /opt/foo
run_make:
  cmd.run:
    - cwd: /opt/foo
    - name: make install
    - watch:
      - git: my_repo