new_contents: # coding: utf8
  from __future__ import unicode_literals
  
  from ...tokens.doc import Doc
  import pytest
  
  
  @pytest.mark.xfail
  @pytest.mark.models
  @pytest.mark.parametrize('text', ["I cant do this."])
  def test_issue636(EN, text):
      """Test that to_bytes and from_bytes don't change the token lemma."""
      doc1 = EN(text)
      doc2 = Doc(EN.vocab)
      doc2.from_bytes(doc1.to_bytes())
      assert doc1[2].lemma_ == doc2[2].lemma_
  
subject: Update regression test