Using :extend with BEM

[dangreen]

This code doesn't work.

.purchase__actions {

    &__cell {
        display: inline-block;
        width: 50%;
        box-sizing: border-box;

        &--full:extend(&) {
            width: 100%;
            padding: 0 15px !important;
        }
    }
}

[seven-phases-max]

See #1554 (as we as #1485 and #2200).

[seven-phases-max]

Closing as a duplicate of #1554.