CRM-15747 Event registration with several payments gets only partially recorded, cannot be edited

I have an individual who registered and paid for an event online via PayPal. Later during the event they provided an additional $200 via cash. The event uses price sets if that matters to allow the user to provide an event fee and a donation amount.

I went into the person's event registration record and increased the donation amount by $200. When I did this, it appeared to correctly set their event registration to "partially paid" and it preserved their PayPal payment contribution information. Then I clicked "Record Payment" and I was able to specify a payment by cash of $200 for this event.

Now the problems come.

1. There is no contribution record created for the user for the $200. There is no contribution record either under the user's Contributions tab of their individual record, nor is there a contribution record under the Contributions section of CiviCRM.

BUT if I go to edit the user's event registration, it shows "Total Fees" is the correct amount including the extra $200. It shows
"Total Paid" is the correct amount that includes original payment and the extra cash, and it shows "Balance" is $0. But below that, it only lists the PayPal payment, not the cash payment. To make things even more confusing, if I click the tiny italicized "View Payments" link underneath the "Balance" field, it does show me the original payment via PayPal, and the second payment via Cash. But that is the ONLY place I can find a record of the payment.

So now I am stuck. I have no way to edit/delete that $200 payment record that only shows up if I look at the payments on the event registration. And I have no contribution record.

I can reproduce this behaviour on the demo site as follows:

1. I created a test event that has a price set.
2. I register a user for the event using online payment. For this example, I had the user want 20 units of each of the price sets.
3. I edit the user's event registration so that they now want 30 units. Now they owe a balance.
4. I add a payment for the user, payment in cash for the balance owing.

The problem is now reproduced. A summary of the problems in this scenario include:

• The user's Contributions show only one entry for the total, but show that one entry as a credit card payment when it was partial card and partial cash.
• The user's event registration only shows the one payment, even though there were two payments.
• The only way to see both payments is by opening their event registration and clicking the very small "view payments" link
• The one payment record shows a payment for the cash+card total but shows the old number of units.
• There is no Contribution record for the second cash payment that I can edit or adjust or even delete.

I believe all of these problems are essentially interrelated. The primary problem is that the Contribution record is not being created for the second cash payment. All of the other problems are a symptom of this central problem.