Can I include the default group to greenkeeper.json when other groups also exist

Background

I've just added a greenekeeper.json file to an already existing (and Greenkeeper enabled) repo to account for additional package.json files that were not previously being monitored by Greenkeeper.

greenkeeper.json

{
  "groups": {
    "default": {
      "packages": [
        "package.json"
      ]
    },
    "libs": {
      "packages": [
        "packages/lib1/package.json",
        "packages/lib2/package.json",
      ]
    }
  }
}

Observation

I see an initial PR for the libs group, but I don't see an initial PR for the default group.

Question

Can I not have a default group, when additional groups (in addition to default) are included?

(i.e. Do I need to rename the default group to something else...?)

Full Disclosure

In my first greenkeeper.json commit, I had included all package.json files in the default group. This commit, predictably, generated an initial Greenkeeper PR, and that PR included library version updates for all package.json files (including root level package.json).

After my second greenkeeper.json commit, Greenkeeper deleted that initial PR, and subsequently created new PRs for each new group, but, it did not generate a PR for the updated default group...so maybe Greenkeeper doesn't create initial PRs for groups that have just been modified (only for those that are newly created)...?

Official response from Greenkeeper (from an email exchange):

An initial branch will only be created for new groups, or groups that have new repositories in them.

Since the default group existed before and there were no new package.json files in that group, no new initial PR commit was created (even though this is the initial greenkeeper.json).

When I re-named that group to root, I did get a new initial PR from Greenkeeper.

Can I not have a default group, when additional groups (in addition to default) are included?

You can have a default group even when there are additional groups in greenkeeper.json.

Do I need to rename the default group to something else...?

Only if you want Greenkeeper to generate a new initial PR.