[llvm][github] Allow github links in /cherry-pick actions

[thieta]

Nice QoL fix here! Thanks!

[thieta]

Oh make sure you run black to check for formatting changes. We don't have the CI hooked up yet.

llvm/utils/git/github-automation.py

for reviewer in reviewers:
         phid = reviewer["reviewerPHID"]
         args = {"constraints[phids][0]": phid}
         # API documentation: https://reviews.llvm.org/conduit/method/user.search/
         r = phab_api_call(phab_token, "https://reviews.llvm.org/api/user.search", args)
         accepted.append(r["result"]["data"][0]["fields"]["username"])
     return accepted
 
 
+def extract_commit_hash(arg: str):
+    """
+    Extract the commit hash from the argument passed to /action github
+    comment actions. We currently only support passing the commit hash
+    directly or use the github URL, such as
+    https://github.com/llvm/llvm-project/commit/2832d7941f4207f1fcf813b27cf08cecc3086959
+    """
+    github_prefix = "https://github.com/llvm/llvm-project/commit/"
+    if arg.startswith(github_prefix):
+        return arg[len(github_prefix) :]
+    return arg
+
+
 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
def execute_command(self) -> bool:
             line.rstrip()
             m = re.search(r"/([a-z-]+)\s(.+)", line)
             if not m:
                 continue
             command = m.group(1)
             args = m.group(2)
 
             if command == "cherry-pick":
-                return self.create_branch(args.split())
+                arg_list = args.split()
+                commits = list(map(lambda a: extract_commit_hash(a), arg_list))
+                return self.create_branch(commits)
 
             if command == "branch":
                 m = re.match("([^/]+)/([^/]+)/(.+)", args)
                 if m:
                     owner = m.group(1)
                     repo = m.group(2)
                     branch = m.group(3)
                     return self.create_pull_request(owner, repo, branch)