`BuildFSSync.walk` relied on an implementation detail to skip traversing
the path ".", relative to the build context dir.
Specifically, it assumed that:
- `URL.parentOf()` would return false when the parent argument was
relative.
- `URL.path(percentEncoded: false)` would preserve the relativity of an
input path.
These assumptions held on earlier macOS releases, so the context
directory silently remained untouched.
In some versions of macOS , `URL.path(percentEncoded: false)` always
returns an absolute path, regardless of how the URL was created. Because
of this change, `URL.parentOf()` now returns true for ".", and
BuildFSSync.walk begins descending into the context directory—something
it was never meant to do.
This solution:
- Remove the hidden dependency on `URL.parentOf()` for context‑directory
detection.
- Add an explicit check for "." inside BuildFSSync.walk and bail out
early.
Replace fragile calls to `URL.path(percentEncoded: false`) with the
stable, documented `URL.relativePath`, which preserves relativity when
the original path was relative.
Patrick Stöckle