Error: @charset may only be used at the root of a document.

[nex3]

From https://github.com/sass/sass/issues/2023:

Take this document one.sass:

@charset "UTF-8"
/*  © Yajo
.other
    @import "other"

Then this another _other.sass:

@charset "UTF-8"
/*  © Yajo
.someclass
    display: none

Then:

sass \
        --cache-location /var/cache/sass\
        --compass\
        --require bootstrap-sass\
        --update /app:/app\

Says:

      error /app/...../static/src/css/_other.sass (Line 1: @charset may only be used at the root of a document.)

... but I need UTF8 for ©! And docs say that @charset only goes into CSS when there's any non-ASCII character, so it should even be automatic.