Editing a contribution from a PCP gets an error saying "soft credit amount cannot be more than the total amount."

To recreate this problem on drupal.demo.civicrm.org,
1) Create a contribution page with a personal campaign page (or use the existing one, if there). Allow Pay later.
2) Make a contribution selecting the pay later option.
3) go to edit the contribution to show that it's completed. You will get an error saying "soft credit amount cannot be more than the total amount." But, in fact, it's not greater than the total amount.