@import Google fonts -> Map issue

Just updated to Sage 8.2 and using SASS.

Simple test (fresh install) :
Compile assets => map source ok in browser.

Add @import url(“http://fonts.googleapis.com/css?family=Open+Sans+Condensed:700”); to _variables.scss
Compile assets => no map source in browser.

I find out that without the import directive, some fonts are working “out of the box”, but others don’t (the one mentioned above don’t).

Any clues on this issue ?