When editing a contribution the value in civicrm_financial_item_amount is not updated

This is something I hit while writing unit tests for CRM-20260 & QAing CRM-19273

When a financial item is edited with a changed amount the value for amount in the civicrm_financial_item.amount value is unchanged. I think it is supposed to be changed. The instructions are exactly the same as replicating either of those issues, but look at the values in civicrm_financial_item.amount - since that is when I spotted it.

Criteria for acceptance is that this line can be uncommented (changing the amount if applicable)

in  tests/phpunit/CRM/Contribute/Form/ContributionTest.php  

// $this->assertEquals(200, $items['values'][2]['amount']);

Any changes that go beyond that should be in separate PRs against separate tickets.

If we need to lock in things that ARE working via tests first we should put those against new tickets too.

(saying all this because the issue has gotten super-confusing0