Add option to playbook to skip worktree(s)
Writers will likely expect files in the working directory (i.e., worktree) to be picked up automatically if the content source points to a directory on the local filesystem. However, there are use cases when the writer will need to run the site only using files committed to the branch. We don't want to force writers to have to stash local changes in this case. Therefore, we should offer a playbook option to disable the worktree. We may need this both globally and per source.
The CLI switch to ignore worktrees globally should be named
--skip-worktree. (I choose this name since it matches a switch in git that offers similar functionality).
This option can also be set on the content key in the playbook spec:
content: skip_worktree: true
or per source:
content: sources: - url: . skip_worktree: true
(We could also consider inverting the switch, so it's
worktree: false instead of