[web2py] import_from_csv_file broken

[Richard Penman]

I exported a table from sqlite with:
open(filename, 'w').write(str(db(db.category.id).select()))

Output file looks as expected.

And then I tried importing into postgres with:
db.category.import_from_csv_file(filename)

Each row was inserted but all values are NULL. 
Any ideas?

Version 1.99.4