Transaction with zero value + fraction is broken

You have a currency (like the default community coins) which allows fractions.

You initiate a transaction with the default 1st party form to initiate this transaction. It only took 1/2 an hour so you enter 0:30 (or whatever you use as fractions).

After the confirmation page you are greeted with an error Units field is required and the transaction lives in the database as validated (but not e.g. pending if you have this activated as the next step).

If you do the same thing with e.g. 1:30 everything works as expected.