Update bedevere/util.py

Co-authored-by: Sven Arends <88426829+picnic-sven@users.noreply.github.com>

Author: Mariatta

bedevere/util.py

@@ -231,10 +231,8 @@ def no_labels(event_data):
         return False
 
 
-async def get_pr_for_commit(gh, sha, repo_full_name=None):
+async def get_pr_for_commit(gh, sha, repo_full_name="python/cpython"):
     """Find the PR containing the specific commit hash."""
-    if not repo_full_name:
-        repo_full_name = "python/cpython"
     prs_for_commit = await gh.getitem(
         f"/search/issues?q=type:pr+repo:{repo_full_name}+sha:{sha}"
     )