Jade bug?

extends.jade

block content

include.jade

mixin test()
  .test&attributes(attributes)

+test()

package.json

{
  "scripts": {
    "postinstall": "echo 'Test 1' && ./node_modules/.bin/jade < test1.jade && echo '' && echo 'Test 2:' &&  ./node_modules/.bin/jade < test2.jade && echo ''"
  },
  "dependencies": {
    "jade": "1.8.2"
  }
}

test1.jade

extends ./extends

block content
  include ./include

test2.jade

extends ./extends

block content
  include ./include
  include ./include

test1.jade output:

<div class="test test"></div>

test2.jade output:

<div class="test"></div><div class="test test"></div>