fix test case

mustache.js

@@ -154,7 +154,10 @@ var Mustache = function() {
            this.send(lines[i]);
          }
        }
-       return lines.join("\n");
+
+       if(in_recursion) {
+         return lines.join("\n");
+       }
     },
 
     set_delimiters: function(delimiters) {

test/mustache_spec.rb

@@ -126,7 +126,7 @@ describe "mustache" do
                 chunks.push(chunk);
               }
             }
-            Mustache.to_html(template, partial_context, partials, null, sendFun);
+            Mustache.to_html(template, partial_context, partials, sendFun);
             print(chunks.join("\\n"));
           } catch(e) {
             print('ERROR: ' + e.message);