Markdown article importer messes up article tree

In a postgres environment articles end up in the wrong place in the article tree.

I created a debug branch which should make things a bit easier to debug and retry quickly.

Instructions to reproduce
Prerequisites

$ bzr branch lp:~developer-ubuntu-com-dev/developer-ubuntu-com/debug-md-importer
$ cd debug-md-importer
$ virtualenv ./env
$ ./env/bin/pip install -r requirements.txt
$ ./env/bin/pip install django psycopg2

This branch mostly just adds some test data, debug messages and some convenience scripts.

To change from sqlite (default) to postgres apply a diff like http://pastebin.ubuntu.com/12798510/ to your developer_portal/settings.py and

$ sudo apt install python-pip python-dev libpq-dev postgresql postgresql-contrib
$ sudo -u postgres psql -c "CREATE USER developerportal_user WITH PASSWORD '123abc';"

The issue itself
Run
$ ./postgres-retry.sh
in a postgres setting and
$ ./sqlite-retry.sh
 in the sqlite setting.

The script will create a new db from scratch, run the importer with debug messages and run runserver for you, so you can easily check in the pages list how the structure changed.

Current state of things:
sqlite does fine and postgres has the article tree messed up.