Drupal 8 doesn't see routes for mailchimp extension
see also: https://github.com/veda-consulting/uk.co.vedaconsulting.mailchimp/issues/321
I get a 404 for all the pages specific to the mailchimp extension, when running under a D8 site.
I'm unsure whether this is a bug in the extension itself, or the civicrm-drupal-8 module, so I thought I'd open an issue here, as well.
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