drop pyversion & is_python3 checking

We're committed to Python 3 at this point, so purge all the
is_python3 related dynamic checks.

Bug: https://crbug.com/gerrit/10418
Change-Id: I4c8b405d6de359b8b83223c9f4b9c8ffa18ea1a2
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/292383
Reviewed-by: Chris Mcdonald <cjmcdonald@google.com>
Tested-by: Mike Frysinger <vapier@google.com>
diff --git a/tests/test_wrapper.py b/tests/test_wrapper.py
index 5e2cfa5..d871373 100644
--- a/tests/test_wrapper.py
+++ b/tests/test_wrapper.py
@@ -15,27 +15,20 @@
 """Unittests for the wrapper.py module."""
 
 import contextlib
+from io import StringIO
 import os
 import re
 import shutil
 import tempfile
 import unittest
+from unittest import mock
 
 import git_command
 import main
 import platform_utils
-from pyversion import is_python3
 import wrapper
 
 
-if is_python3():
-  from unittest import mock
-  from io import StringIO
-else:
-  import mock
-  from StringIO import StringIO
-
-
 @contextlib.contextmanager
 def TemporaryDirectory():
   """Create a new empty git checkout for testing."""
@@ -62,9 +55,6 @@
     wrapper._wrapper_module = None
     self.wrapper = wrapper.Wrapper()
 
-    if not is_python3():
-      self.assertRegex = self.assertRegexpMatches
-
 
 class RepoWrapperUnitTest(RepoWrapperTestCase):
   """Tests helper functions in the repo wrapper