No way to merge with sass stream

[marcinant]

I would like to use gulp-wpstylecss with gulp-sass:

return wpstylecss()
.pipe(addsrc('style.scss'))
.pipe(sass())
.pipe(gulp.dest('./dest'))

This code should output style.css with header generated by gulp-wpstylecss and css as result of sass compilation. Unfortunately it results with css only. No header at all.