R1:d78c22640b08

Change Duplicate icon in Maniphest

Summary: Fixes T7917

Test Plan: Closed a task as a duplicate, see new icon.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T7917

Differential Revision: https://secure.phabricator.com/D12575