Allow caching in unsafe mode, but disable in safe mode.

lib/jekyll/converters/sass.rb

@@ -38,10 +38,14 @@ module Jekyll
       )
     end
 
+    def allow_caching?
+      !@config["safe"]
+    end
+
     def sass_configs(content = "")
       sass_build_configuration_options({
         "syntax" => syntax_type_of_content(content),
-        "cache"  => false,
+        "cache"  => allow_caching?,
         "load_paths" => [sass_dir_relative_to_site_source]
       })
     end

test/test_sass.rb

@@ -54,8 +54,14 @@ CSS
   end
 
   context "when building configurations" do
-    should "not allow caching" do
+    should "not allow caching in safe mode" do
-      assert_equal false, converter.sass_configs[:cache]
+      verter = converter
+      verter.instance_variable_get(:@config)["safe"] = true
+      assert_equal false, verter.sass_configs[:cache]
+    end
+
+    should "allow caching in unsafe mode" do
+      assert_equal true, converter.sass_configs[:cache]
     end
 
     should "set the load paths to the _sass dir relative to site source" do
@@ -85,10 +91,6 @@ CSS
     should "override user-set syntax based on content" do
       assert_equal :sass, converter({"syntax" => :scss}).sass_configs(sass_content)[:syntax]
     end
-
-    should "override user-set cache setting" do
-      assert_equal false, converter("cache" => true).sass_configs[:cache]
-    end
   end
 
   context "converting sass" do