reference_order not being padded in database

[acholyn]

reference_order (for original texts) does not seem to undergo the clean_reference_order function to pad the numbers such that 10.17 would be stored as 00010.00017 in the database.

[tcouch]

I've discovered that explicitly running form._post_clean() during OriginalTextUpdateView's form_valid() method fixes the problem, but _post_clean should have been triggered when the form.is_valid property is checked.

closing, but opening #348 to investigate why this is necessary