fix(upstream-triage): skip new upstream files inside a directory the fork removed (#656)

* fix(upstream-triage): skip new upstream files inside a directory the fork removed

A path absent from both HEAD and the merge base was always counted as new
upstream work, so a file added inside a tree the fork deleted (a test added
to a dropped portal) put the commit under "Worth reviewing" with a
cherry-pick that can only conflict. The nearest existing ancestor directory
now decides: present in HEAD means new work in a kept directory, present
only at the base means the fork removed the tree.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* changelog: place the #656 entry under [Unreleased]

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
Co-authored-by: Mads Lorentzen <madslorentzen_17@hotmail.com>

CHANGELOG.md

@@ -156,6 +156,15 @@ per-file diff commands.
   `administrativeRegion` filter (2,486 jobs for `Region Midtjylland`), and the docs map each `locations`
   category to its flag and give `--region` examples that exist.
 
+- **`upstream_triage.py` skips a new upstream file inside a directory the fork removed**
+  (#656, follow-up to #585, `tools/upstream_triage.py`, `tests/test_upstream_triage.py`) - #585 counted
+  every path absent from both HEAD and the merge base as new upstream work, so a file added
+  inside a removed tree landed under "Worth reviewing": on a fork that dropped
+  `.agents/skills/jobnet-search/`, #586 (which adds a test file there and edits a source file
+  that is also gone) was listed with a ready-to-run cherry-pick that can only conflict. A new
+  path now counts as removed when its nearest ancestor directory exists at the base but not
+  in HEAD; a new file or subdirectory under a directory the fork kept is still worth reviewing.
+
 ## [1.7.3] - 2026-10-19
 
 ### Added