Fixing flake8 errors.

Author: rwgk

tests/test_pytypes.py

@@ -254,7 +254,7 @@ def test_pybind11_str_raw_str():
     valid_orig = u"DZ"
     valid_utf8 = valid_orig.encode("utf-8")
     valid_cvt = cvt(valid_utf8)
-    assert type(valid_cvt) == type(u"")  # Py2 unicode, Py3 str, flake8 compatible
+    assert type(valid_cvt) is unicode if pytest.PY2 else str  # noqa: F821
     if pytest.PY2:
         assert valid_cvt == valid_orig
     else:
@@ -267,7 +267,7 @@ def test_pybind11_str_raw_str():
         assert "invalid start byte" in str(excinfo)
     else:
         malformed_cvt = cvt(malformed_utf8)
-        assert type(valid_cvt) == type(u"")
+        assert type(malformed_cvt) is unicode if pytest.PY2 else str  # noqa: F821
         assert malformed_cvt == u"b'\\x80'"