Prevent race condition when duplicate conversion requests are done in parallel

convert.py

@@ -311,6 +311,13 @@ def convert(
                 )
 
             if operations:
+                # Checking that no PR have been created during the conversion in case of duplicate conversion requests.
+                pr = previous_pr(api, model_id, pr_title, revision=revision)
+                if pr is not None and not force:
+                    url = f"https://huggingface.co/{model_id}/discussions/{pr.num}"
+                    new_pr = pr
+                    raise AlreadyExists(f"Model {model_id} already has an open PR check out {url}")
+                    
                 new_pr = api.create_commit(
                     repo_id=model_id,
                     revision=revision,