Ask HN: Why does Coveralls need to write to my repo?

I'm familiar with how Travis (and presumably other CIs) write to a repo's "status" to indicate broken builds. This morning, coveralls.io asked for perms to do the same thing, which seemed cool. After I approved that, it then asked for "read and write all public and private repo data". Github says that perm includes writing the following:

  Code
  Issues
  Pull requests
  Wikis
  Settings
  Webhooks and services
  Deploy keys

And also Coveralls has set up a redirect loop so that if I don't submit to this indignity, I can't use that site at all. Anyone have any ideas about this?