openlayers/openlayers — comment on commit b351734cf642193b0469d0cd0bd330e90f946db4
File: lib/OpenLayers/Request/XMLHttpRequest.js line 252
By elemoine:

This is actually fixed upstream. https://github.com/ilinsky/xmlhttprequest/commit/9f1d0fd49b0583073c1ca19e220dc13fe0f509b4. So we should just update the code in OpenLayers.