---

- name: Execute pre-commands
  command: '{{ item.pre_command.command }}'
  args:
    chdir: '{{ item.pre_command.chdir | default(item.dest) }}'
  when: item.pre_command is defined

- name: Checkout git repo
  git:
    repo: '{{ item.repo }}'
    dest: '{{ item.dest }}'
    force: 'yes'
    key_file: '{{ item.key_file | default(omit) }}'
    version: '{{ item.version | default("HEAD") }}'
  register: git_checkout

- name: Execute post-commands
  command: '{{ item.post_command.command }}'
  args:
    chdir: '{{ item.post_command.chdir | default(item.dest) }}'
  when: item.post_command is defined and git_checkout.changed

...