Revert "Merge branch 'debug'"

This reverts commit 89b79d1178, reversing
changes made to 02bdf490a1.

spacy/tests/regression/test_issue636.py

@@ -1,16 +0,0 @@
-# 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_