Bug with handling / in interpolation

[xzyfer]

@nex3 confirmed this is a bug. There is currently a sass spec asserting this broken behaviour which is causing LibSass to fail CI.

h1 {
  delayd: #{5% / 2};
  delayd: #{+5% / 2};
  evaled: #{-5% / 2};
}

Sass 3.4.21

h1 {
  delayd: 5%/2;
  delayd: 5%/2;
  evaled: -2.5%;
}

Expected

h1 {
  delayd: 5%/2;
  delayd: 5%/2;
  evaled: -5%/2;
}

[nex3]

I'm moving this issue to the new Ruby Sass repository because it's specific to Ruby Sass's implementation.