Check Suite webhook payload has incorrect `before` SHA when branch contains a '/'


Hi, we’re listening to Check Suite webhooks and we’ve noticed that if a branch contains a forward slash (like feature/my-feature) then the before SHA is all zeroes:

  "action": "requested",
  "check_suite": {
    "id": 18402969,
    "node_id": "MDEwOkNoZWNrU3VpdGUxODQwMjk2OQ==",
    "head_branch": "bugfix/rename-android",
    "head_sha": "88b9fa2f3130ebf8a9d870b91ca7b0a5921844ea",
    "status": "queued",
    "conclusion": null,
    "url": "",
    "before": "0000000000000000000000000000000000000000",
    "after": "88b9fa2f3130ebf8a9d870b91ca7b0a5921844ea",

We believe this is a bug as branches without a slash give us the before SHA as expected.