title: Jinja PackageLoader raises "unregistered loader type" on Python 3
body: <p>I was playing with around with the <a href="http://jinja.pocoo.org/docs/2.9/api/#basics" rel="nofollow noreferrer">jinja basics</a>.</p>
  
  <pre><code>from jinja2 import Environment, PackageLoader, select_autoescape
  env = Environment(
      loader=PackageLoader('yourapplication', 'templates'),
      autoescape=select_autoescape(['html', 'xml']
  )
  </code></pre>
  
  <p>Then I do:</p>
  
  <pre><code>template = env.get_template('some_dir_in_templates/mytemplate.html')
  </code></pre>
  
  <p>which works in Python 2 just fine - I believe this is to be expected since I understand that there are bugs when using with python 3 ... something I fear is the case here. </p>
  
  <p>But when I run the later code in Python 3 I get:</p>
  
  <pre><code>Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
    File "/usr/local/lib/python3.4/dist-packages/jinja2/environment.py", line 830, in get_template
      return self._load_template(name, self.make_globals(globals))
    File "/usr/local/lib/python3.4/dist-packages/jinja2/environment.py", line 804, in _load_template
      template = self.loader.load(self, name, globals)
    File "/usr/local/lib/python3.4/dist-packages/jinja2/loaders.py", line 113, in load
      source, filename, uptodate = self.get_source(environment, name)
    File "/usr/local/lib/python3.4/dist-packages/jinja2/loaders.py", line 234, in get_source
      if not self.provider.has_resource(p):
    File "/usr/local/lib/python3.4/dist-packages/pkg_resources/__init__.py", line 1455, in has_resource
      return self._has(self._fn(self.module_path, resource_name))
    File "/usr/local/lib/python3.4/dist-packages/pkg_resources/__init__.py", line 1505, in _has
      "Can't perform this operation for unregistered loader type"
  NotImplementedError: Can't perform this operation for unregistered loader type
  </code></pre>
  
  <p>Are there any solutions or workarounds in order to fix or make this function in Python 3.4.3?</p>
  
  <p>I am using Jinja 2.9.6</p>