Last modified: 2014-08-03 11:24:58 UTC
Take any article long enough to notice the effect (i.e. Cake on en.wp). Delete any of the pics at the bottom of the article. Notice the focus jumps back at the top.
It also happens with templates, so I'm guessing this is probably worrying but maybe a duplicate.
Change 151400 had a related patch set uploaded by Jforrester: Set selection before focusing document https://gerrit.wikimedia.org/r/151400
Change 151400 merged by jenkins-bot: Set selection before focusing document https://gerrit.wikimedia.org/r/151400