Don't report test results for closed PRs

When doing a try run, bors will often push the last closed merge onto
the branch before pushing the change to try. This means that test
results get reported on closed PRs. There are two issues with this:

1. Doing too much work on the bots.
2. Extra results on closed PRs.

This changes fixes the second issue.

Fixes #29583.

etc/ci/report_aggregated_expected_results.py

@@ -153,6 +153,11 @@ def get_github_run_url() -> Optional[str]:
     return f"[#{run_id}](https://github.com/{repository}/actions/runs/{run_id})"
 
 
+def is_pr_open(pr_number: str) -> bool:
+    return b"open" == subprocess.check_output(
+        ["gh", "api", f"/repos/servo/servo/pulls/{pr_number}", "--template", "{{.state}}"])
+
+
 def get_pr_number() -> Optional[str]:
     github_context = json.loads(os.environ.get("GITHUB_CONTEXT", "{}"))
     if "event" not in github_context:
@@ -161,20 +166,29 @@ def get_pr_number() -> Optional[str]:
         return None
     commit_title = github_context["event"]["head_commit"]["message"]
     match = re.match(r"^Auto merge of #(\d+)", commit_title)
-    return match.group(1) if match else None
+
+    if not match:
+        return None
+
+    # Only return a PR number if the PR is open. bors will often push old merges
+    # onto the HEAD of try branches and we don't want to return results for these
+    # old PRs.
+    number = match.group(1)
+    return number if is_pr_open(number) else None
 
 
-def create_check_run(body: str, tag: str):
+def create_check_run(body: str, tag: str = ""):
+    # This process is based on the documentation here:
     # https://docs.github.com/en/rest/checks/runs?apiVersion=2022-11-28#create-a-check-runs
-    conclusion = 'neutral'
-    # get conclusion
     results = json.loads(os.environ.get("RESULTS", "{}"))
-    if "cancelled" in results:
-        conclusion = 'cancelled'
-    if "failure" in results:
-        conclusion = 'failure'
     if all(r == 'success' for r in results):
         conclusion = 'success'
+    elif "failure" in results:
+        conclusion = 'failure'
+    elif "cancelled" in results:
+        conclusion = 'cancelled'
+    else:
+        conclusion = 'neutral'
 
     github_token = os.environ.get("GITHUB_TOKEN")
     github_context = json.loads(os.environ.get("GITHUB_CONTEXT", "{}"))
@@ -193,11 +207,9 @@ def create_check_run(body: str, tag: str):
         'output': {
             'title': f'Aggregated {tag} report',
             'summary': body,
-            # 'text': '',
             'images': [{'alt': 'WPT logo', 'image_url': 'https://avatars.githubusercontent.com/u/37226233'}]
         },
         'actions': [
-            # {'label': 'Fix', 'identifier': 'fix_errors', 'description': 'Allow us to fix these errors for you'}
         ]
     }