fix: fetch remote branch before checkout in update-copilot-dependency workflow

[Copilot]

git push --force-with-lease fails with "stale info" when the workflow re-runs against an already-existing remote branch, because the local remote-tracking ref is never populated before the push.

Changes

• .github/workflows/update-copilot-dependency.yml: In the existing-branch path, add git fetch origin "$BRANCH" before checkout and reset to origin/$BRANCH (instead of HEAD) so --force-with-lease has accurate tracking info.

# Before
if git rev-parse --verify "origin/$BRANCH" >/dev/null 2>&1; then
  git checkout "$BRANCH"
  git reset --hard HEAD
else
  git checkout -b "$BRANCH"
fi

# After
if git rev-parse --verify "origin/$BRANCH" >/dev/null 2>&1; then
  git fetch origin "$BRANCH"
  git checkout "$BRANCH"
  git reset --hard "origin/$BRANCH"
else
  git checkout -b "$BRANCH"
fi

Original prompt

The "Update @github/copilot Dependency" workflow fails when the remote branch already exists because git push --force-with-lease rejects the push due to stale tracking info.

Failing job: https://github.com/github/copilot-sdk/actions/runs/24489964719/job/71572769209

Error:

! [rejected]  update-copilot-1.0.28 -> update-copilot-1.0.28 (stale info)
error: failed to push some refs to 'https://github.com/github/copilot-sdk'

Root cause: In .github/workflows/update-copilot-dependency.yml, lines 81-86, when the remote branch already exists, the workflow checks it out and resets to HEAD but never fetches the remote branch first. This means --force-with-lease has stale ref info and rejects the push.

Fix: Update the existing-branch path (around lines 81-86) to fetch the remote branch before checking it out:

          if git rev-parse --verify "origin/$BRANCH" >/dev/null 2>&1; then
            git fetch origin "$BRANCH"
            git checkout "$BRANCH"
            git reset --hard "origin/$BRANCH"
          else
            git checkout -b "$BRANCH"
          fi

Key changes:

1. Add git fetch origin "$BRANCH" to ensure the local remote-tracking ref is current.
2. Change git reset --hard HEAD to git reset --hard "origin/$BRANCH" so the local branch matches the fetched remote state, allowing --force-with-lease to succeed.

The following is the prior conversation context from the user's chat exploration (may be truncated):

User: Please find a solution for this failing job. Use the logs, job definition, and any referenced files where the failure occurred. Keep your response focused on the solution and include code suggestions when appropriate.

Assistant: ## Failing Job Analysis

The job fails at line 100 when pushing the branch:

! [rejected]  update-copilot-1.0.28 -> update-copilot-1.0.28 (stale info)
error: failed to push some refs to 'https://github.com/github/copilot-sdk'

Cause

git push origin "$BRANCH" --force-with-lease fails because the remote branch update-copilot-1.0.28 already exists, but the local checkout doesn't have up-to-date tracking info for it. On lines 81–86, when the branch already exists remotely, the workflow does git checkout "$BRANCH" and git reset --hard HEAD, but it never fetches the remote branch first. This means --force-with-lease sees stale ref info and rejects the push.

Solution

Fetch the remote branch before checking it out so the local ref matches the remote, allowing --force-with-lease to work correctly. Update the workflow at line 81:

          if git rev-parse --verify "origin/$BRANCH" >/dev/null 2>&1; then
            git fetch origin "$BRANCH"
            git checkout "$BRANCH"
            git reset --hard "origin/$BRANCH"
          else
            git checkout -b "$BRANCH"
          fi

Key changes:

1. git fetch origin "$BRANCH" — ensures the local remote-tracking ref is current.
2. git reset --hard "origin/$BRANCH" — resets to the fetched remote state (not just local HEAD), so subsequent --force-with-lease has the correct base.

This ensures the push won't be rejected due to stale tracking information when the branch already exists from a previous run.

User: Create a PR to fix it

Assistant: I've started creating a pull request to fix the workflow. The coding agent is working on updating .github/workflows/update-copilot-dependency.yml to fetch the remote branch before checkout, which will resolve the --force-with-lease stale info rejection. I'll share the PR link once it's ready.

This pull request was created from Copilot chat.

[Copilot]

Pull request overview

Fixes re-run failures in the “Update @github/copilot Dependency” workflow where git push --force-with-lease can be rejected due to stale/missing remote-tracking information for an already-existing remote branch.

Changes:

• Fetch the target remote branch before checkout in the existing-branch path.
• Reset the local branch to origin/$BRANCH instead of HEAD when the remote branch is detected.

Show a summary per file

File	Description
.github/workflows/update-copilot-dependency.yml	Attempts to ensure up-to-date remote-tracking refs before force-with-lease pushes during dependency update PR automation.

Copilot's findings

• Files reviewed: 1/1 changed files
• Comments generated: 2

[Copilot]

git rev-parse --verify "origin/$BRANCH" only checks for a local remote-tracking ref. On a fresh Actions checkout this ref typically won’t exist for non-default branches, so this condition can still be false even when the remote branch exists—meaning the new git fetch origin "$BRANCH" never runs and --force-with-lease can remain stale. Consider checking remote existence via git ls-remote --exit-code --heads origin "$BRANCH" (or attempting an explicit refspec fetch and branching on its exit code), then fetching +refs/heads/$BRANCH:refs/remotes/origin/$BRANCH to ensure the tracking ref is populated/updated.

Suggested change

	if git rev-parse --verify "origin/$BRANCH" >/dev/null 2>&1; then
	git fetch origin "$BRANCH"
	if git ls-remote --exit-code --heads origin "$BRANCH" >/dev/null 2>&1; then
	git fetch origin "+refs/heads/$BRANCH:refs/remotes/origin/$BRANCH"

[Copilot]

git reset --hard "origin/$BRANCH" will discard the dependency/codegen changes produced by the earlier workflow steps (since this runs after the update/format steps). If the intent is only to refresh remote-tracking info for --force-with-lease, avoid a hard reset here; alternatively stash changes before switching/resetting and re-apply them, or move the branch checkout/reset logic earlier (before modifications are made).