fix: unset stale GH_HOST when configuring gh for github.com

[Copilot]

configure_gh_for_ghe.sh returned early for github.com without clearing GH_HOST, leaving any stale GHE host value in place. Downstream gh commands (e.g., gh pr checkout) would then fail with none of the git remotes correspond to the GH_HOST environment variable.

Changes

• actions/setup/sh/configure_gh_for_ghe.sh: When the resolved host is github.com, explicitly clear a stale GH_HOST value — unset GH_HOST in the current shell and write GH_HOST= to $GITHUB_ENV to clear it for subsequent steps.

if [ "$github_host" = "github.com" ]; then
  echo "Using public GitHub (github.com) - no additional gh configuration needed"
  # Clear any stale GH_HOST to prevent gh CLI mismatches
  if [ -n "${GH_HOST:-}" ] && [ "${GH_HOST}" != "github.com" ]; then
    echo "Clearing stale GH_HOST" >&2
    unset GH_HOST
    if [ -n "${GITHUB_ENV:-}" ]; then
      echo "GH_HOST=" >> "${GITHUB_ENV}"
    fi
  fi
  return 0
fi

The guard (GH_HOST set and not already github.com) ensures no-ops when GH_HOST is already correct or unset. The log message omits the stale value to avoid leaking internal hostnames or risking workflow-command injection. The GITHUB_ENV write uses an empty assignment (GH_HOST=) to fully clear the variable for subsequent steps, consistent with the pattern used in stop_difc_proxy.sh.

[Copilot]

Pull request overview

Fixes a GitHub CLI host mismatch when running on github.com by clearing/overriding a stale GH_HOST value that could otherwise cause downstream gh commands (e.g., gh pr checkout) to fail.

Changes:

• When the resolved host is github.com, detect and clear a stale GH_HOST value.
• Persist the corrected host setting for later GitHub Actions steps via $GITHUB_ENV.

---

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[Copilot]

echo "Clearing stale GH_HOST=${GH_HOST}" will print the previous (potentially internal) GHE hostname into GitHub Actions logs when running on github.com. If these workflows run in public repos, this can leak internal infrastructure details; additionally, echoing raw environment values risks accidental workflow-command injection if GH_HOST ever contains ::... sequences. Consider omitting the value (log a generic message), or at least writing the message to stderr and sanitizing the value before printing.

Suggested change

	echo "Clearing stale GH_HOST=${GH_HOST}"
	echo "Clearing stale GH_HOST" >&2

[Copilot]

This block says it is clearing a stale GH_HOST, but for subsequent steps it writes GH_HOST=github.com into $GITHUB_ENV (so GH_HOST remains set rather than cleared). Elsewhere in this repo, clearing GH_HOST for later steps is done by writing an empty assignment (e.g., actions/setup/sh/stop_difc_proxy.sh:28 uses GH_HOST=). Consider using the same clearing pattern here (or adjust the comment/message to reflect that the intent is to force GH_HOST to github.com, not clear it).

Suggested change

	echo "GH_HOST=github.com" >> "${GITHUB_ENV}"
	echo "GH_HOST=" >> "${GITHUB_ENV}"

[pelikhan]

@copilot review comments

[Copilot]

@copilot review comments

Addressed both review comments in 634d533:

• Log message no longer prints the stale GH_HOST value (written to stderr as a generic message)
• GITHUB_ENV now writes GH_HOST= to clear the variable for subsequent steps, consistent with stop_difc_proxy.sh