Sass @error @debug @warn directives don't create proper output?

In my Eclipse Luna environment I’m calling Vaadin Sass compiler from inside a batch file via command-line command described here:

Unfortunately, when I use lines like

@debug $variable;

the console log result is

INFORMATION: $variable

and not the actual contents of $variable.

Likewise @warn “Some text #{$variable}”; comes out as: “Some text #{$variable}
Everything else is compiling just fine.

Is there any parameter I’m missing?

Edit: I’ve tried using vaadin.sass.compiler versions 0.9.10 and 0.9.13 with identical results.

Same here, did also not fnd any solution yet.