In 7d40a7d, f820c07, 3ed0628 the way the mobile preview iframe is set
was altered several times. This left an inconsistent needless page load.
This page load was cancelled, but as a side effect in a given set of
conditions:
- an ajax request is done early in current (and so iframe) page,
- phantomjs is used for the test,
- server response time
this could lead to a false positive caused by a cancelled xhr request
throwing the error: "Can't load template, http status 0".
e03d64cfaa