Revert back to the previous Sass path

- This was changed in 73b09f6
- It seemed to intermittently break the importing of Bourbon in Rails apps

CHANGELOG.md

@@ -7,6 +7,11 @@ project adheres to [Semantic Versioning](http://semver.org).
 
 [Unreleased]: https://github.com/thoughtbot/bourbon/compare/v5.0.0.beta.4...HEAD
 
+### Fixed
+
+- Fixed a Sass load path issue that would intermittently break the importing of
+  Bourbon in Rails apps.
+
 ### Changed
 
 - Swapped the order of the `$file-formats` and `$asset-pipeline` arguments in

lib/bourbon.rb

@@ -1,4 +1,7 @@
 require "bourbon/generator"
 
 bourbon_path = File.expand_path("../../core", __FILE__)
-ENV["SASS_PATH"] = File.join([ENV["SASS_PATH"], bourbon_path].compact)
+ENV["SASS_PATH"] = [
+  ENV["SASS_PATH"],
+  bourbon_path,
+].compact.join(File::PATH_SEPARATOR)