Variable concatenation with interpolation adds a space in between

[ausi]

Concatenating a variable with an interpolation like $input#{$input} shouldn’t add a space between them.

$input: literal;
.result {
  output: $input#{$input};
}

Should generate this output, as RubySass does:

.result {
  output: literalliteral; }

The actual output of LibSass 3.2.2 is:

.result {
  output: literal literal; }

A complete test case of all combinations of literal, $input, #{$input}, #{literal}, #{"literal"} can be found here: sass/sass-spec/tree/1a35b2b/spec/parser/interpolate/01_literal/07_variable_concatenation

The correct behavior is described in sass/sass#1704 (comment)