…erges (#65765) (#65851)

* CI: Notify open PRs that conflict on uv.lock after main merges

When `uv.lock` changes on `main`, open PRs that touch `uv.lock` frequently
end up with rebase conflicts. This adds a workflow that, on each push to
`main` that modifies `uv.lock`, scans open non-draft PRs (updated in the
last 14 days), identifies those currently reporting conflicts, and posts
(or updates, deduped via an HTML-comment marker) a single comment with
rebase-and-`uv lock` instructions.

The source PR that caused the change is resolved from the squash-merge
commit headline's trailing `(#NNN)` and linked in the notice.

Implemented as a standalone PEP 723 Python script (`httpx` + GitHub's
GraphQL API) so logic stays testable; workflow YAML is a thin driver that
installs `uv` from `uv.lock` and runs the script. Unit tests cover the
regex, classifier, pagination/early-exit, UNKNOWN-mergeable retry loop,
and notice posting.

* Fix scripts-tests by stubbing httpx in unit-test module

The scripts-project CI venv doesn't have httpx installed, so importing
``notify_uv_lock_conflicts`` fails with ``ModuleNotFoundError: No module
named 'httpx'`` before any test runs. httpx is a PEP 723 runtime dep of
the script; the tests mock the client and never need the real library.

Stub ``httpx`` in ``sys.modules`` with ``setdefault`` before loading the
module under test: keeps the scripts distribution's declared deps
unchanged, and leaves real ``httpx`` alone when present (e.g. in the
workspace-wide dev environment).
(cherry picked from commit 4fae29c)

Co-authored-by: Jarek Potiuk <jarek@potiuk.com>

…erges (#65765) (#65851)

* CI: Notify open PRs that conflict on uv.lock after main merges

When `uv.lock` changes on `main`, open PRs that touch `uv.lock` frequently
end up with rebase conflicts. This adds a workflow that, on each push to
`main` that modifies `uv.lock`, scans open non-draft PRs (updated in the
last 14 days), identifies those currently reporting conflicts, and posts
(or updates, deduped via an HTML-comment marker) a single comment with
rebase-and-`uv lock` instructions.

The source PR that caused the change is resolved from the squash-merge
commit headline's trailing `(#NNN)` and linked in the notice.

Implemented as a standalone PEP 723 Python script (`httpx` + GitHub's
GraphQL API) so logic stays testable; workflow YAML is a thin driver that
installs `uv` from `uv.lock` and runs the script. Unit tests cover the
regex, classifier, pagination/early-exit, UNKNOWN-mergeable retry loop,
and notice posting.

* Fix scripts-tests by stubbing httpx in unit-test module

The scripts-project CI venv doesn't have httpx installed, so importing
``notify_uv_lock_conflicts`` fails with ``ModuleNotFoundError: No module
named 'httpx'`` before any test runs. httpx is a PEP 723 runtime dep of
the script; the tests mock the client and never need the real library.

Stub ``httpx`` in ``sys.modules`` with ``setdefault`` before loading the
module under test: keeps the scripts distribution's declared deps
unchanged, and leaves real ``httpx`` alone when present (e.g. in the
workspace-wide dev environment).
(cherry picked from commit 4fae29c)

Co-authored-by: Jarek Potiuk <jarek@potiuk.com>