pub fn apply_outer_gitignore(
start: &Path,
ignore_path: &Path,
) -> Result<OuterRepoOutcome>Expand description
Walk upward from start looking for an outer .git/ directory; on
success append ignore_path (rendered relative to the outer root)
to that repo’s .gitignore. The starting directory is the parent of
the new gitdir / mem-repo so we don’t rediscover our own git.
ignore_path must lie inside the discovered outer repo for the
relative-path rendering to succeed; if strip_prefix fails the
helper returns OuterRepoOutcome::NoOuter defensively rather than
emit a garbled rule.
Refuses with a Validation error when the discovered outer root
equals $HOME. Callers are expected to render the error verbatim
or surface the --no-gitignore suggestion themselves.