Incorrect Contribution Summary Report when a contributions has multiple soft credits

In prior versions of CiviCRM it was only possible to enter one soft credit per contribution. Now it is possible to enter any number of soft credits. Unfortunately CRM_Report_Form_Contribute_Summary does a left join with the civicrm_contribution_soft table. When there was only one soft credit per contribution, the left join was fine, but now having the left join with multiple soft credits duplicates the original contribution record in the summary report.

So if I have a donation for $100 with zero or one soft credit, it shows up as $100 in the contribution summary report. If I add a second soft credit (with any amount), the total shows up as $200. If I add a third soft credit (with any amount), the total shows up as $300.

I was able to reproduce this on the demo site.