[workflow] Don't fail workflow if we already have a PR for an issue

[thieta]

Summary

When running /cherry-pick several times you will get an
error when it tries to create a new PR since there already
is one.

This checks if we have PR first.

Fixes #54862

[thieta]

Removed unintentional debug lines

[tstellar]

llvm/utils/git/github-automation.py

15

Do we need these if we already have import github ?

195

I think you can access the pull request directly based on the head branch: repo.get_pull(head='owner:branch')

[thieta]

Updates

[thieta]

Remove unused parameter

llvm/utils/git/github-automation.py

15

I think vscode was adding this because I used them in the type-hinting below. I removed the lines again.

195

Yeah I changed it to that now - but this can in theory return multiple PR's. I wonder if we need to handle this better if we get multiple matches. But I struggled to see how that would matter.

[thieta]

@tstellar ping - should we merge this now?

[tstellar]

Sorry for the delay, I though this was merged already. LGTM.

llvm/utils/git/github-automation.py

 #!/usr/bin/env python3
 #
 # ======- github-automation - LLVM GitHub Automation Routines--*- python -*--==#
 #
 # Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 # See https://llvm.org/LICENSE.txt for license information.
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 #
 # ==-------------------------------------------------------------------------==#
 
 import argparse
 from git import Repo # type: ignore
 import github
 import os
 import re
 import sys
 from typing import *
 
 class IssueSubscriber:
 
     @property
     def team_name(self) -> str:
         return self._team_name
def create_branch(self, commits:List[str]) -> bool:
         push_url = self.push_url
         print('Pushing to {} {}'.format(push_url, branch_name))
         local_repo.git.push(push_url, 'HEAD:{}'.format(branch_name), force=True)
 
         self.issue_notify_branch()
         self.issue_remove_cherry_pick_failed_label()
         return True
 
+    def check_if_pull_request_exists(self, repo:github.Repository.Repository, head:str) -> bool:
+        pulls = repo.get_pulls(head=head)
+        return pulls != None
 
     def create_pull_request(self, owner:str, branch:str) -> bool:
         """
         reate a pull request in `self.branch_repo_name`.  The base branch of the
         pull request will be choosen based on the the milestone attached to
         the issue represented by `self.issue_number`  For example if the milestone
         is Release 13.0.1, then the base branch will be release/13.x. `branch`
         will be used as the compare branch.
         https://docs.github.com/en/get-started/quickstart/github-glossary#base-branch
         https://docs.github.com/en/get-started/quickstart/github-glossary#compare-branch
         """
         repo = github.Github(self.token).get_repo(self.branch_repo_name)
         issue_ref = '{}#{}'.format(self.repo_name, self.issue_number)
         pull = None
         release_branch_for_issue = self.release_branch_for_issue
         if release_branch_for_issue is None:
             return False
+        head = f"{owner}:{branch}"
+        if self.check_if_pull_request_exists(repo, head):
+            print("PR already exists...")
+            return True
         try:
-            pull = repo.create_pull(title='PR for {}'.format(issue_ref),
+            pull = repo.create_pull(title=f"PR for {issue_ref}",
                                     body='resolves {}'.format(issue_ref),
                                     base=release_branch_for_issue,
-                                    head='{}:{}'.format(owner, branch),
+                                    head=head,
                                     maintainer_can_modify=False)
         except Exception as e:
             self.issue_notify_pull_request_failure(branch)
             raise e
 
         if pull is None:
             return False