Output of @extend and :not() selector are wrong

[ghost]

Hi. I have a problem with compile this code

.test {
	.test2 {
		@extend .btn;
	}
}
.btn {
    display: none;
}
.text-box {
    display: none;
    a:not(.btn) {
    	display: none;
        &:hover {
            display: none;
        }
    }
}

Output CSS:

.btn, .test .test2 {
  display: none; }

.text-box {
  display: none; }
  .text-box a:not(.btn):not(.test .test2) {
    display: none; }
    .text-box a:not(.btn):not(.test .test2):hover {
      display: none; }

There is a problem with a correct write in multiply classes with :not selector.
"gulp-sass": "^3.1.0"
In SassMeister output is correct http://prntscr.com/dwsxqf

Could you please check this?

[xzyfer]

Tracking this upstream in sass/libsass#2139