@import (reference) copies import directives

[chharvey]

When File A uses @import (reference) on File B, and File B itself has its own @import (css) directive, say for normalize.css, this directive gets copied into File A.

This is bad if I'm trying to chain imports and use @import (reference) in combo with @import (css). Example:

// site.less
@import (css) url('normalize.css');
// some other mixins and classes here

/* output site.css */
@import url('normalize.css'); /* as expected */

// page.less
@import (css) url('site.css');        // page.css needs styles from site.css but don't want them injected inline
@import (reference) url('site.less'); // now page.less can use the mixins defined in site.less

/* output page.css */
@import url('site.css');      /* as expected, and site.css already has `@import url ('normalize.css')` thus the "chaining" */
@import url('normalize.css'); /* not expected! probably because of the (reference) keyword */

Now I have two imports of normalize.css, and this gets complicated if page.less and site.less are in different directories.