Issue Import: TypeError: string indices must be integers

I wanted to import issues from my Trac project. In the end, I wrote a python script to build what I thought was a compliant db-1.0.json file. But I am stymied by the error message mentioned in the title.

(and yes, I did read https://confluence.atlassian.com/pages/viewpage.action?pageId=330796872 closely)

I tried to reduce the import to the minimal set required to reproduce the problem. In the end it is very minimal indeed!

#!json

{ "components" : [ "website" ],
  "issues" : [ { "assignee" : "unayok",
        "component" : "website",
        "content" : "Content.",
        "content_updated_on" : "2009-01-18T09:55:21.000000+00:00",
        "created_on" : "2009-01-18T09:55:01.000000+00:00",
        "edited_on" : "2009-01-18T09:55:21.000000+00:00",
        "id" : 1,
        "kind" : "task",
        "milestone" : "creation",
        "priority" : "critical",
        "reporter" : "unayok",
        "status" : "resolved",
        "title" : "Title",
        "updated_on" : "2009-01-18T09:55:21.000000+00:00"
      }
    ],
  "meta" : { "default_assignee" : "unayok",
      "default_component" : "website",
      "default_kind" : "bug"
    },
  "milestones" : [ "creation" ],
  "versions" : [ "1.0" ]
}

The much more complete export also failed (with a complement of "comments", "log" but no "attachments"). I expect either there's a bug that needs fixing or the documentation on imports needs to be clearer as to the requirements. The only idea that comes to mind is that the 'id' is not unique from BitBucket's overall perspective. This isn't discussed either way in the document.

I don't mind meeting tough guidelines for creating an import file as long as they're documented. I think there's an actual bug here though. Better error messages would be useful too.