Financial Transaction with Payment = 0 Listed in Partially Paid Contribution Detail

As I was testing CRM-17408, I noticed some oddities with the financial transactions listed when clicking the black arrow next to the partially paid contribution (as seen in the attached screenshot):

1. Looking in the DB, both financial transactions are marked is completed and understandably so (or at least I think it is understandable) - one is the completed partial payment, and the other is the receivable, and I am assuming that the underlying financial account configuration will be able to figure out that $18 is still due
2. Note, however, that there is also an indication whether a transaction is a payment or not - in discussing with Eileen, the only transactions that should be listed in the contribution details in the GUI are completed payments, not completed non-payments.

This issue may be closely related to other issues being seen with membership payments (sorry - don't have ticket #).

@KarinG