Release Workflow: Remove cherry-pick-failed label when pull request is created

[nikic]

LGTM, thanks!

llvm/utils/git/github-automation.py

def setup_llvmbot_git(git_dir = '.'):
     """
     repo = Repo(git_dir)
     with repo.config_writer() as config:
         config.set_value('user', 'name', 'llvmbot')
         config.set_value('user', 'email', '[e-mail]')
 
 class ReleaseWorkflow:
 
+    CHERRY_PICK_FAILED_LABEL = 'release:cherry-pick-failed'
+
     """
     This class implements the sub-commands for the release-workflow command.
     The current sub-commands are:
         * create-branch
         * create-pull-request
 
     The execute_command method will automatically choose the correct sub-command
     based on the text in stdin.
class ReleaseWorkflow:
     def issue_notify_cherry_pick_failure(self, commit:str) -> github.IssueComment.IssueComment:
         message = "<!--IGNORE-->\nFailed to cherry-pick: {}\n\n".format(commit)
         action_url = self.action_url
         if action_url:
             message += action_url + "\n\n"
         message += "Please manually backport the fix and push it to your github fork.  Once this is done, please add a comment like this:\n\n`/branch <user>/<repo>/<branch>`"
         issue = self.issue
         comment = issue.create_comment(message)
-        issue.add_to_labels('release:cherry-pick-failed')
+        issue.add_to_labels(self.CHERRY_PICK_FAILED_LABEL)
         return comment
 
     def issue_notify_pull_request_failure(self, branch:str) -> github.IssueComment.IssueComment:
         message = "Failed to create pull request for {} ".format(branch)
         message += self.action_url
         return self.issue.create_comment(message)
 
+    def issue_remove_cherry_pick_failed_label(self):
+        if self.CHERRY_PICK_FAILED_LABEL in [l.name for l in self.issue.labels]:
+            self.issue.remove_from_labels(self.CHERRY_PICK_FAILED_LABEL)
 
     def create_branch(self, commits:List[str]) -> bool:
         """
         This function attempts to backport `commits` into the branch associated
         with `self.issue_number`.
 
         If this is successful, then the branch is pushed to `self.branch_repo_name`, if not,
         a comment is added to the issue saying that the cherry-pick failed.
def create_branch(self, commits:List[str]) -> bool:
                 self.issue_notify_cherry_pick_failure(c)
                 raise e
 
         push_url = self.push_url
         print('Pushing to {} {}'.format(push_url, branch_name))
         local_repo.git.push(push_url, 'HEAD:{}'.format(branch_name))
 
         self.issue_notify_branch()
+        self.issue_remove_cherry_pick_failed_label()
         return True
 
 
     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
def create_pull_request(self, owner:str, branch:str) -> bool:
         except Exception as e:
             self.issue_notify_pull_request_failure(branch)
             raise e
 
         if pull is None:
             return False
 
         self.issue_notify_pull_request(pull)
+        self.issue_remove_cherry_pick_failed_label()
 
         # TODO(tstellar): Do you really want to always return True?
         return True
 
 
     def execute_command(self) -> bool:
         """
         This function reads lines from STDIN and executes the first command