fix(ci): use GET for rerun freshness check

[lokidundun]

Purpose of the PR

• close #xxx

Main Changes

Root Cause

The gh api command included -f and -F parameters without specifying an HTTP method. GitHub CLI therefore switched the request from GET to POST, causing the commits endpoint to return 404 Not Found.

The error response was assigned to latest_head_sha and subsequently written to $GITHUB_OUTPUT, producing the following error:

Unable to process file command 'output' successfully.
Invalid format '  "message": "Not Found",\r'

As a result, the workflow failed at the Check source branch freshness step before gh run rerun could be executed.

Previous Failures

The same error can be found in the following Rerun CI runs:

• Rerun CI #3
• Rerun CI #5
• Rerun CI #7
• Rerun CI #12
• Rerun CI #15

Add --method GET to the source branch freshness API request.
Ensure the sha and per_page parameters are sent as GET query parameters.

Verifying these changes

• Trivial rework / code cleanup without any test coverage. (No Need)
• Already covered by existing tests, such as (please modify tests here).
• Need tests and can be verified as follows.

Does this PR potentially affect the following parts?

• Nope
• Dependencies (add/update license info)
• Modify configurations
• The public API
• Other affects (typed here)

Documentation Status

• Doc - TODO
• Doc - Done
• Doc - No Need

[imbajin]

Blocking: yes. Summary: The explicit GET fixes the request method, but the new error handling breaks the intended branch-deleted skip path. Evidence: querying the commits endpoint for a missing branch returns HTTP 404 with exit code 1, which terminates this set -euo pipefail step before the fallback runs.

[imbajin]

⚠️ This removes the failure guard from a command substitution that runs under set -euo pipefail. When the source branch has been deleted or is inaccessible, this GET returns HTTP 404 with exit code 1, so the step exits here and never reaches the intended action="skip" / reason="head branch no longer available" handling below. Please keep --method GET, but capture the command failure explicitly (for example with an if ! latest_head_sha="$(...)"; then ... fi) and convert the expected branch-gone case into a safe skip without allowing the error response into $GITHUB_OUTPUT.

[imbajin]

Blocking: no. Summary: The explicit GET now preserves the intended branch-unavailable skip path under set -euo pipefail, with no remaining actionable findings. Evidence: three independent review lanes, static shell control-flow verification, and all visible latest-head checks are green. Score: 9.3/10.