Themes: Bail if the search term matches the currently rendered themes, Fixes the events being clobbered. Props jblz. Fixes #26347

Built from https://develop.svn.wordpress.org/trunk@26521


git-svn-id: http://core.svn.wordpress.org/trunk@26414 1a063a9b-81f0-0310-95a4-ce76da25c4cd