Add test workspace setup role

This will allow us to test changes to this role which is used in base
and base-test.

Change-Id: I072eea647313aac5c5f1024db193b603ad91e010

roles/test-mirror-workspace-git-repos/README.rst

@@ -0,0 +1,6 @@
+Mirror the local git repos to remote nodes
+
+This role uses git operations (unlike :zuul:role:`prepare-workspace`
+which uses rsync) to mirror the local prepared git repos to the remote
+nodes.  This may be useful if the remote node already has a copy of
+some or all of the git repos.

roles/test-mirror-workspace-git-repos/tasks/main.yaml

@@ -0,0 +1,42 @@
+- name: Allow pushing to non-bare repo
+  git_config:
+    name: receive.denyCurrentBranch ignore
+    value: ignore
+    scope: local
+    repo: "{{ ansible_user_dir }}/{{ item.value.src_dir}}"
+  with_dict: "{{ zuul.projects }}"
+
+- name: Synchronize src repos to workspace directory
+  command: "git push --mirror git+ssh://{{ ansible_user }}@{{ ansible_host }}/{{ ansible_user_dir }}/{{ item.value.src_dir}}"
+  args:
+    chdir: "{{ zuul.executor.work_root }}/{{ item.value.src_dir }}"
+  with_dict: "{{ zuul.projects }}"
+  delegate_to: localhost
+  # We occasionally see git pushes in the middle of this loop fail then
+  # subsequent pushes for other repos succeed. The entire loop ends up
+  # failing because one of the pushes failed. Mitigate this by retrying
+  # on failure.
+  register: git_push
+  until: git_push is success
+  retries: 3
+  # ANSIBLE0006: Skip linting since it triggers on the "git" command,
+  # but push is not supported by ansible git module.
+  tags:
+    - skip_ansible_lint
+
+# Do this as a multi-line shell so that we can do the loop once
+- name: Update remote repository state correctly
+  shell: |
+    # Reset is needed because we pushed to a non-bare repo
+    git reset --hard
+    # Undo the config setting we did above
+    git config --local --unset receive.denyCurrentBranch
+    # checkout the branch matching the branch set up by the executor
+    git checkout {{ item.value.checkout }}
+  args:
+    chdir: "{{ ansible_user_dir }}/{{ item.value.src_dir }}"
+  with_dict: "{{ zuul.projects }}"
+  # ANSIBLE0006: Skip linting since it triggers on the "git" command,
+  # but we prefer the shell above
+  tags:
+    - skip_ansible_lint