i got "Unexpected token COLON found" with this code:

@mixin img-retina($file-1x, $file-2x, $width-1x, $height-1x) {
  background-image: url(if($bootstrap-sass-asset-helper, twbs-image-path("#{$file-1x}"), "#{$file-1x}"));

and this one also

@font-face {
  font-family: 'Glyphicons Halflings';
  src: url(if($bootstrap-sass-asset-helper, twbs-font-path('#{$icon-font-path}#{$icon-font-name}.eot'), '#{$icon-font-path}#{$icon-font-name}.eot'));
  src: url(if($bootstrap-sass-asset-helper, twbs-font-path('#{$icon-font-path}#{$icon-font-name}.eot?#iefix'), '#{$icon-font-path}#{$icon-font-name}.eot?#iefix')) format('embedded-opentype'),

as you can see in the attachments.

But the sass compilation is fine and the output file is correct. The sass source is from bootstrap-sass github project with no modification.