Getting eligible reviewers doesn't work for outside collaborators(?)

When I run spr diff with Reviewers: sven-of-cord I get an error saying that that's not an eligible reviewer.

Getting the list of eligible reviewers is done by the API repos/OWNER/REPO/collaborators. When I run this API on this repo, I get a list that doesn't include sven-of-cord. I only get:

[
  {
    "login": "oyamauchi",
    "id": 107014,
    "node_id": "MDQ6VXNlcjEwNzAxNA==",
    ...urls...
    "type": "User",
    "site_admin": false,
    "permissions": {
      "admin": false,
      "maintain": false,
      "push": true,
      "triage": true,
      "pull": true
    },
    "role_name": "write"
  },
  {
    "login": "flooey",
    "id": 215991,
    "node_id": "MDQ6VXNlcjIxNTk5MQ==",
    ...urls...
    "type": "User",
    "site_admin": false,
    "permissions": {
      "admin": true,
      "maintain": true,
      "push": true,
      "triage": true,
      "pull": true
    },
    "role_name": "admin"
  },
  {
    "login": "jacksongabbard",
    "id": 544550,
    "node_id": "MDQ6VXNlcjU0NDU1MA==",
    ...urls...
    "type": "User",
    "site_admin": false,
    "permissions": {
      "admin": true,
      "maintain": true,
      "push": true,
      "triage": true,
      "pull": true
    },
    "role_name": "admin"
  }
]

I'm not sure why this is happening, but I suspect it's a permissions issue, because I'm an outside collaborator, not a member of the organization?

spacedentist / spr

Getting eligible reviewers doesn't work for outside collaborators(?) #97