This one is not that hard to plug, but I'd like to know more about the contents of se_u. It is strange that user_type is None. It's possible that this user account is unusual in some way.
There is something that can save you time: the importer script has two options that allow you to separately read the dump and process the data. Use --help option to find out more.
Also - you can save yourself some time by using sqlite3 database engine for your test imports, as the database file can be simply copied to save the data and avoid re-reading it.