Revert "Push multiple branches in the stack atomically: it's faster, plus possible improves CODEOWNERS processing by GitHub"

This reverts commit fb9c1b1.

Author: dimikot

git-grok

@@ -86,16 +86,6 @@ class Pr:
     labels: list[str]
 
 
-#
-# A pair of commit hash and branch name.
-#
-@dataclass
-class Branch:
-    hash: str
-    branch: str
-    push_result: BranchPushResult | None = None
-
-
 #
 # Some data passed from the main process to each individual child process call
 # within "git rebase -i", for each commit in the stack.
@@ -237,8 +227,6 @@ class Main:
                     commit_with_no_url = commit
                     break
                 else:
-                    # Push this branch and see whether GitHub says whether it
-                    # was up to date or not.
                     commit_hashes_to_push_branch.append(commit.hash)
 
         # Some commits have no related PRs (no GitHub URLs in the message)?
@@ -282,36 +270,23 @@ class Main:
 
         self.print_header(f"Processing commit: {self.clean_title(commit.title)}")
 
-        to_push: list[Branch] = []
-
         if prev_commit.hash != remote_commit.hash:
-            prev_commit.branch = self.process_commit_infer_branch(commit=prev_commit)
-            to_push.append(Branch(hash=prev_commit.hash, branch=prev_commit.branch))
-        else:
-            prev_commit.branch = None
-
-        commit.branch = self.process_commit_infer_branch(commit=commit)
-        to_push.append(Branch(hash=commit.hash, branch=commit.branch))
-
-        push_results = self.git_push_branches(branches=to_push)
-
-        if prev_commit.branch:
+            prev_commit, result = self.process_commit_push_branch(commit=prev_commit)
             self.print_branch_result(
                 type="base",
-                branch=prev_commit.branch,
-                result=push_results[prev_commit.branch],
+                branch=str(prev_commit.branch),
+                result=result,
             )
         else:
             self.print_branch_result(
                 type="base",
                 branch=self.remote_base_branch,
                 result="up-to-date",
             )
-        self.print_branch_result(
-            type="head",
-            branch=commit.branch,
-            result=push_results[commit.branch],
-        )
+            prev_commit.branch = None
+
+        commit, result = self.process_commit_push_branch(commit=commit)
+        self.print_branch_result(type="head", branch=str(commit.branch), result=result)
 
         new_pr_title = commit.title
         new_pr_body = None
@@ -367,11 +342,11 @@ class Main:
         commits: list[Commit],
         prs_by_url: dict[str, Pr],
     ):
-        commits_old_to_new = list(reversed(commits))
-        for i, commit in list(enumerate(commits_old_to_new))[1:]:
+        commits_chronological = list(reversed(commits))
+        for i, commit in list(enumerate(commits_chronological))[1:]:
             pr = prs_by_url.get(commit.url, None) if commit.url else None
             if pr and pr.auto_merge_status == "ENABLED":
-                prev_commit = commits_old_to_new[i - 1]
+                prev_commit = commits_chronological[i - 1]
                 prev_pr = (
                     prs_by_url.get(prev_commit.url, None) if prev_commit.url else None
                 )
@@ -451,35 +426,25 @@ class Main:
     ):
         # We must iterate from the oldest commit to the newest one, because
         # previous commit PR's branch becomes the next commit PR's base branch.
-        commits_old_to_new = list(reversed(commits))
-
-        # Push all branches atomically, in bulk. This is meant to prevent
-        # useless CODEOWNERS reviewers addition in case the commits were
-        # reordered or rebased, and is faster in general.
-        to_push: list[Branch] = []
-        for commit in commits_old_to_new:
-            if (
-                self.debug_force_push_branches
-                or commit.hash in commit_hashes_to_push_branch
-            ):
-                commit.branch = self.process_commit_infer_branch(commit=commit)
-                to_push.append(Branch(hash=commit.hash, branch=commit.branch))
-        push_results = self.git_push_branches(branches=to_push)
-
-        for i, commit in enumerate(commits_old_to_new):
+        commits_chronological = list(reversed(commits))
+        for i, commit in enumerate(commits_chronological):
             self.print_header(f"Updating PR: {self.clean_title(commit.title)}")
 
-            if commit.branch in push_results:
-                result = push_results[commit.branch]
+            if commit.hash in commit_hashes_to_push_branch:
+                commit, result = self.process_commit_push_branch(commit=commit)
                 if result == "pushed":
                     self.print_branch_result(
                         type="head",
-                        branch=commit.branch,
+                        branch=str(commit.branch),
                         result=result,
                     )
+                commits_chronological[i] = commit
 
+            assert (
+                commit.url is not None
+            ), f"commit {commit.hash} PR url is expected to be in the message at this point"
             pr, result = self.process_update_pr(
-                prev_commit=commits_old_to_new[i - 1] if i > 0 else None,
+                prev_commit=commits_chronological[i - 1] if i > 0 else None,
                 commit=commit,
                 commits=commits,
             )
@@ -488,26 +453,27 @@ class Main:
                 result=result,
                 review_decision=pr.review_decision,
             )
-            commits_old_to_new[i].branch = pr.head_branch
+            commits_chronological[i].branch = pr.head_branch
 
     #
-    # For a commit, infers its corresponding remote branch name by either
-    # querying it from the PR (when commit.url is set), or by building it from
-    # the commit title and hash.
+    # Pushes an existing branch (it we know this commit's PR URL by querying
+    # GitHub), or creates a new branch based on commit title and pushes it.
     #
-    def process_commit_infer_branch(
+    def process_commit_push_branch(
         self,
         *,
         commit: Commit,
-    ) -> str:
+    ) -> tuple[Commit, BranchPushResult]:
         if commit.url:
-            pr = self.gh_get_pr(url=commit.url)  # likely a cache hit
-            return pr.head_branch
+            pr = self.gh_get_pr(url=commit.url)
+            commit.branch = pr.head_branch
         else:
-            return self.build_branch_name(
+            commit.branch = self.build_branch_name(
                 title=commit.title,
                 commit_hash=commit.hash,
             )
+        pushed = self.git_push_branch(branch=commit.branch, hash=commit.hash)
+        return commit, pushed
 
     #
     # Updates PR fields:
@@ -898,14 +864,9 @@ class Main:
         return commits
 
     #
-    # Pushes multiple branches atomically to remote GitHub. Returns a dict
-    # mapping branch names to their push results.
+    # Pushes a branch to remote GitHub.
     #
-    def git_push_branches(
-        self,
-        *,
-        branches: list[Branch],
-    ) -> dict[str, BranchPushResult]:
+    def git_push_branch(self, *, branch: str, hash: str) -> BranchPushResult:
         # Git push is a quick no-op on GitHub end if the branch isn't changed
         # (it prints "Everything up-to-date"), so we always push and then verify
         # the output for the status (instead of fetching from the remote and
@@ -916,26 +877,15 @@ class Main:
                 "push",
                 "-f",
                 self.remote,
-                *[f"{branch.hash}:refs/heads/{branch.branch}" for branch in branches],
+                f"{hash}:refs/heads/{branch}",
             ],
             stderr_to_stdout=True,
         )
-        # If the hash is NOT mentioned in the output, it's either a short
-        # "Everything up-to-date" message (which means that ALL branches are
-        # unchanged), or THIS particular branch is up-to-date. I.e. if a branch
-        # is changed, git always prints its hash in the output, on one of the
-        # following formats:
-        # 1. * [new branch] 10dc4f6 -> grok/...
-        # 2. + 10dc4f6...b28d03e 10dc4f6 -> grok/... (forced update)
-        results: dict[str, BranchPushResult] = {
-            branch.branch: "up-to-date" for branch in branches
-        }
-        for branch in branches:
-            for line in out.splitlines():
-                if branch.hash in line:
-                    results[branch.branch] = "pushed"
-                    break
-        return results
+        return (
+            "up-to-date"
+            if re.match(r"^[^\n]+up-to-date", out, flags=re.S)
+            else "pushed"
+        )
 
     #
     # Runs an interactive rebase with the provided shell command.
@@ -1197,7 +1147,7 @@ class Main:
     # Prints a status after a commit message was updated locally.
     #
     def print_commit_message_updated(self):
-        print(f"  ── added PR URL to commit's message to bind them")
+        print(f"  ── updated commit message")
         sys.stdout.flush()
 
     #