Update merge-flow config for vs18.7 release branch

[SimaTian]

Phase 1.3 of MSBuild Release Checklist 18.7.

Insert vs18.7 as the last entry before main in the merge chain so that fixes flow vs18.6 → vs18.7 → main after vs18.7 is branched.

⚠️ Do not merge until vs18.7 branch exists (Phase 1.1).

cc @rainersigwald

[Copilot]

Pull request overview

Updates MSBuild’s merge-flow configuration to include the upcoming vs18.7 release branch in the servicing merge chain, enabling automated forward merges to flow vs18.6 → vs18.7 → main once the branch exists.

Changes:

• Insert vs18.7 into the merge chain as the target for vs18.6.
• Add a new vs18.7 configuration that forwards merges to main.

[github-actions]

Review Summary

The semantic change is correct — inserting vs18.7 between vs18.6 and main in the merge chain is exactly what's needed for the 18.7 release, and the comments are accurate.

Issue: CRLF line endings stored in git blob

Severity: Should fix before merge

The committed blob changed from LF to CRLF line endings. This is confirmed by comparing git cat-file -p output between origin/main and the PR branch — the old blob uses 0a (LF) while the new blob uses 0d 0a (CRLF). File sizes: 1929 bytes (old, LF) → 2170 bytes (new, CRLF).

This causes:

• The diff shows a full-file rewrite (46 deletions, 50 additions) instead of the ~4-line actual change
• Inconsistency with the repo's * text=auto .gitattributes setting, which expects LF in the object store
• Unnecessary git history churn

The fix is simple: re-normalize the file so LF endings are stored in the blob (see inline comment for commands).

Merge prerequisite ✅

The PR description correctly warns: "Do not merge until vs18.7 branch exists." Confirmed that vs18.7 does not yet exist — this is expected and properly documented.

Generated by Expert Code Review (on open) for issue #13643 · ● 2.7M

Addressed in follow-up commit a15cf81 — CRLF rewritten to LF; current diff is the intended +5/-1 minimal change.