(also, sorry if I misfiled this, it was my best guess :))

Actually, the reason is the following: you have CLs in your checkout that are associated with Rietveld CLs. In this case, this code is executed:

class _RietveldChangelistImpl(_ChangelistCodereviewBase):

  def __init__(self, changelist, auth_config=None, codereview_host=None):
    super(_RietveldChangelistImpl, self).__init__(changelist)
    assert settings, 'must be initialized in _ChangelistCodereviewBase'
    if ¬codereview_host:
      settings.GetDefaultServerUrl()

This is only true if the repository both
a) has no CODE_REVIEW_SERVER in its codereview.settings; *and*
b) your local checkout has a branch which is uploaded to Rietveld

If you have no branches uploaded to Rietveld, it doesn't try to figure out what Rietveld host to talk to.

This bug will naturally disappear as we remove rietveld support from git-cl. I don't plan to mess with anyone's codereview.settings until after that's complete, so no one else should run into this problem.

Ah! That's totally the case. I was actually running the tool to see which
branches I needed to reupload :p.

No one else has complained about this, and a lot of the Rietveld code has been ripped out.