Add commits-since function

nixprstatus/pr.py

@@ -23,6 +23,14 @@ def commit_in_branch(commit_sha: str, branch: str) -> bool:
     return False
 
 
+def commits_since(first_ref: str, last_ref: str) -> int:
+    url = f"https://api.github.com/repos/NixOS/nixpkgs/compare/{first_ref}...{last_ref}"
+    commit_response = requests.get(url, headers=DEFAULT_HEADERS)
+    commit_response.raise_for_status()
+
+    return commit_response.json()["behind_by"]
+
+
 def pr_merge_status(pr: int, branches: list[str] = DEFAULT_BRANCHES) -> PRStatus:
     url = f"https://api.github.com/repos/NixOS/nixpkgs/pulls/{pr}"
     pr_response = requests.get(url, headers=DEFAULT_HEADERS)