While working on MDL-63244, a couple of details about the new 3.7 dependencies loader were found:

1) as far as the new dep loader (MDL-64348) is called with nologin... there is no session, hence language always was defaulting to the site lang. The issue fixed that by explicitly adding the page lang to the dep loader. All ok, so far.

2) it was also noticed that the string-cache being used is not lang-aware. And that rasied some thoughts about which is its behavior when the user changes of language ...

As far as 2) was well out from the scope of MDL-63244, it was decided to create this, so we can verify which is current behavior on lang-switching situations, how the js lang string-cache behaves and if we need any change on it (or not). Just to avoid missing it.

That's all, ciao