Don't notify about changing to the same state it was at
Summary:
The object tracker was telling me it's notifying the same value it
already got, and reading the code it seems to be already notifying when it
actually changes.
Test Plan: tests pass, plasma runs fine.
Reviewers: Plasma
Subscribers: kde-frameworks-devel
Tags: Frameworks
Differential Revision: https://phabricator.kde.org/D21481