Weird behaviour of `@extend` with `%` placeholder selectors.

_imp1.scss

@import "inc";

.imp1 {
    @extend %test;
}

_imp2.scss

@import "inc";

.imp2 {
    @extend %test;
}

_imp3.scss

@import "inc";

.imp3 {
    @extend %test;
}

_inc.scss

%test {
    color: red;
}

main.css

.imp1, .imp2, .imp3 {
  color: red; }

.imp1, .imp2, .imp3 {
  color: red; }

.imp1, .imp2, .imp3 {
  color: red; }

main.scss

@import "imp1";
@import "imp2";
@import "imp3";