feat(github-actions): only request branch manager checks for prs that need it

Only request the branch manager to check the pull requests that target the same branch as the branch that
was updated for `push` events.

Author: josephperrott

github-actions/branch-manager/lib/main.ts

@@ -16,27 +16,29 @@ async function run() {
       return;
     }
 
-    if (ref !== 'refs/heads/main') {
-      // TODO: support pushes to all releasable branches rather than just main.
-      core.info('Skipping evaluation as the push does not affect the main branch');
-      return;
-    }
-
     core.info(`Evaluating pull requests as a result of a push to '${ref}'`);
 
-    const mergeReadyPrQuery =
-      `repo:${context.repo.owner}/${context.repo.repo} ` +
-      `is:pr ` +
-      `is:open ` +
-      `label:"${actionLabels.ACTION_MERGE.name}"`;
-
     const prs = await github().then((api) =>
       api.paginate(
-        api.search.issuesAndPullRequests,
+        api.pulls.list,
         {
-          q: mergeReadyPrQuery,
+          repo: context.repo.repo,
+          owner: context.repo.owner,
+          state: 'open',
+          per_page: 100,
+        },
+        (pulls) => {
+          return pulls.data
+            .filter(({labels, base}) => {
+              return (
+                // Whether the pull request is slated to merge into the same branch as the triggering push.
+                base.ref === ref &&
+                // Whether the pull request has the action: merge label.
+                labels.some(({name}) => name === actionLabels.ACTION_MERGE.name)
+              );
+            })
+            .map(({number}) => `${number}`);
         },
-        (issues) => issues.data.map((i) => `${i.number}`),
       ),
     );
     core.info(`Triggering ${prs.length} prs to be evaluated`);