[GHF] Add co-authors to PR (#118347)

Mention co-authors in PR body

Modify `CommitAuthors` to include query first two commit `authors`, which makes sure that authors from suggested commits are recognized.

Test plan: CI + check `get_authors()` on a few PRs
Pull Request resolved: https://github.com/pytorch/pytorch/pull/118347
Approved by: https://github.com/kit1980

.github/scripts/test_trymerge.py

@@ -434,6 +434,13 @@ class TestTryMerge(TestCase):
         assert pr._reviews is not None  # to pacify mypy
         self.assertGreater(len(pr._reviews), 100)
 
+    def get_co_authors(self, *args: Any) -> None:
+        """Tests that co-authors are recognized"""
+        pr = GitHubPR("pytorch", "pytorch", 118347)
+        authors = pr.get_authors()
+        self.assertIn("kit1980", authors)
+        self.assertIn("Co-authored-by:", pr.gen_commit_message())
+
     def test_get_checkruns_many_runs(self, *args: Any) -> None:
         """Tests that all checkruns can be fetched"""
         pr = GitHubPR("pytorch", "pytorch", 105260)

.github/scripts/trymerge.py

@@ -152,12 +152,14 @@ GH_COMMIT_AUTHORS_FRAGMENT = """
 fragment CommitAuthors on PullRequestCommitConnection {
   nodes {
     commit {
-      author {
-        user {
-          login
+      authors(first: 2) {
+        nodes {
+          user {
+            login
+          }
+          email
+          name
         }
-        email
-        name
       }
       oid
     }
@@ -846,14 +848,14 @@ class GitHubPR:
 
         def add_authors(info: Dict[str, Any]) -> None:
             for node in info["commits_with_authors"]["nodes"]:
-                author_node = node["commit"]["author"]
-                user_node = author_node["user"]
-                author = f"{author_node['name']} <{author_node['email']}>"
-                if user_node is None:
-                    # If author is not github user, user node will be null
-                    authors.append(("", author))
-                else:
-                    authors.append((cast(str, user_node["login"]), author))
+                for author_node in node["commit"]["authors"]["nodes"]:
+                    user_node = author_node["user"]
+                    author = f"{author_node['name']} <{author_node['email']}>"
+                    if user_node is None:
+                        # If author is not github user, user node will be null
+                        authors.append(("", author))
+                    else:
+                        authors.append((cast(str, user_node["login"]), author))
 
         info = self.info
         for _ in range(100):
@@ -949,11 +951,6 @@ class GitHubPR:
 
     def get_authors(self) -> Dict[str, str]:
         rc = {}
-        # TODO: replace with  `self.get_commit_count()` when GraphQL pagination can be used
-        # to fetch all commits, see https://gist.github.com/malfet/4f35321b0c9315bcd7116c7b54d83372
-        # and https://support.github.com/ticket/enterprise/1642/1659119
-        if self.get_commit_count() <= 250:
-            assert len(self._fetch_authors()) == self.get_commit_count()
         for idx in range(len(self._fetch_authors())):
             rc[self.get_committer_login(idx)] = self.get_committer_author(idx)
 
@@ -1115,6 +1112,12 @@ class GitHubPR:
             msg_body = re.sub(RE_GHSTACK_DESC, "", msg_body)
         msg = self.get_title() + f" (#{self.pr_num})\n\n"
         msg += msg_body
+
+        # Mention PR co-authors
+        for author_login, author_name in self.get_authors().items():
+            if author_login != self.get_pr_creator_login():
+                msg += f"\nCo-authored-by: {author_name}"
+
         msg += f"\nPull Request resolved: {self.get_pr_url()}\n"
         msg += f"Approved by: {approved_by_urls}\n"
         if ghstack_deps: