angular/angular.js — pull request #6986 by shahata (2014-04-03 23:37:30+00:00)
Title: fix(booleanAttrs): remove attribute when empty value instead of ignoring

this will allow updating the values of ng-src, ng-srcset, ng-href back to empty state while preserving the intended behavior of not setting the attribute to an empty string to prevent behavior like trying to download the current page as an image or creating a link to the current page.

Fixes https://github.com/angular/angular.js/issues/2755