Fields duplicating on save

Using the latest HEAD from CVS, I'm noticing that field definitions are sometimes duplicated on save, in the admin page (admin/settings/views_calc).

To reproduce:

• Create a valid, new field, for example I just created a field called 'month' with Calculation: DATE_PART( 'month', TO_TIMESTAMP(%accesslog.timestamp) ) (note: this is PostgreSQL specific, so just work out whatever the equivalent is for MySQL).
• Change some part of the newly created field and Save.
• The field should be duplicated. If it's not, it may also be necessary to get the form validation to generate an error (in my case I tried adding a field that used database functions that were yet to be defined in the Settings) before trying 2. then nearly every edit will double the number of fields.

This would be bearable, if it weren't for the lack of a delete button! Anyway, that's what I get for using HEAD I suppose. ;)