diff --git a/python/ez_setup.py b/python/ez_setup.py
deleted file mode 100644
index 955a800..0000000
--- a/python/ez_setup.py
+++ /dev/null
@@ -1,332 +0,0 @@
-#!/usr/bin/env python
-"""Bootstrap setuptools installation
-
-To use setuptools in your package's setup.py, include this
-file in the same directory and add this to the top of your setup.py::
-
-    from ez_setup import use_setuptools
-    use_setuptools()
-
-To require a specific version of setuptools, set a download
-mirror, or use an alternate download directory, simply supply
-the appropriate options to ``use_setuptools()``.
-
-This file can also be run as a script to install or upgrade setuptools.
-"""
-import os
-import shutil
-import sys
-import tempfile
-import zipfile
-import optparse
-import subprocess
-import platform
-import textwrap
-import contextlib
-
-from distutils import log
-
-try:
-    from urllib.request import urlopen
-except ImportError:
-    from urllib2 import urlopen
-
-try:
-    from site import USER_SITE
-except ImportError:
-    USER_SITE = None
-
-DEFAULT_VERSION = "11.3.1"
-DEFAULT_URL = "https://pypi.python.org/packages/source/s/setuptools/"
-
-def _python_cmd(*args):
-    """
-    Return True if the command succeeded.
-    """
-    args = (sys.executable,) + args
-    return subprocess.call(args) == 0
-
-
-def _install(archive_filename, install_args=()):
-    with archive_context(archive_filename):
-        # installing
-        log.warn('Installing Setuptools')
-        if not _python_cmd('setup.py', 'install', *install_args):
-            log.warn('Something went wrong during the installation.')
-            log.warn('See the error message above.')
-            # exitcode will be 2
-            return 2
-
-
-def _build_egg(egg, archive_filename, to_dir):
-    with archive_context(archive_filename):
-        # building an egg
-        log.warn('Building a Setuptools egg in %s', to_dir)
-        _python_cmd('setup.py', '-q', 'bdist_egg', '--dist-dir', to_dir)
-    # returning the result
-    log.warn(egg)
-    if not os.path.exists(egg):
-        raise IOError('Could not build the egg.')
-
-
-class ContextualZipFile(zipfile.ZipFile):
-    """
-    Supplement ZipFile class to support context manager for Python 2.6
-    """
-
-    def __enter__(self):
-        return self
-
-    def __exit__(self, type, value, traceback):
-        self.close()
-
-    def __new__(cls, *args, **kwargs):
-        """
-        Construct a ZipFile or ContextualZipFile as appropriate
-        """
-        if hasattr(zipfile.ZipFile, '__exit__'):
-            return zipfile.ZipFile(*args, **kwargs)
-        return super(ContextualZipFile, cls).__new__(cls)
-
-
-@contextlib.contextmanager
-def archive_context(filename):
-    # extracting the archive
-    tmpdir = tempfile.mkdtemp()
-    log.warn('Extracting in %s', tmpdir)
-    old_wd = os.getcwd()
-    try:
-        os.chdir(tmpdir)
-        with ContextualZipFile(filename) as archive:
-            archive.extractall()
-
-        # going in the directory
-        subdir = os.path.join(tmpdir, os.listdir(tmpdir)[0])
-        os.chdir(subdir)
-        log.warn('Now working in %s', subdir)
-        yield
-
-    finally:
-        os.chdir(old_wd)
-        shutil.rmtree(tmpdir)
-
-
-def _do_download(version, download_base, to_dir, download_delay):
-    egg = os.path.join(to_dir, 'setuptools-%s-py%d.%d.egg'
-                       % (version, sys.version_info[0], sys.version_info[1]))
-    if not os.path.exists(egg):
-        archive = download_setuptools(version, download_base,
-                                      to_dir, download_delay)
-        _build_egg(egg, archive, to_dir)
-    sys.path.insert(0, egg)
-
-    # Remove previously-imported pkg_resources if present (see
-    # https://bitbucket.org/pypa/setuptools/pull-request/7/ for details).
-    if 'pkg_resources' in sys.modules:
-        del sys.modules['pkg_resources']
-
-    import setuptools
-    setuptools.bootstrap_install_from = egg
-
-
-def use_setuptools(version=DEFAULT_VERSION, download_base=DEFAULT_URL,
-        to_dir=os.curdir, download_delay=15):
-    to_dir = os.path.abspath(to_dir)
-    rep_modules = 'pkg_resources', 'setuptools'
-    imported = set(sys.modules).intersection(rep_modules)
-    try:
-        import pkg_resources
-    except ImportError:
-        return _do_download(version, download_base, to_dir, download_delay)
-    try:
-        pkg_resources.require("setuptools>=" + version)
-        return
-    except pkg_resources.DistributionNotFound:
-        return _do_download(version, download_base, to_dir, download_delay)
-    except pkg_resources.VersionConflict as VC_err:
-        if imported:
-            msg = textwrap.dedent("""
-                The required version of setuptools (>={version}) is not available,
-                and can't be installed while this script is running. Please
-                install a more recent version first, using
-                'easy_install -U setuptools'.
-
-                (Currently using {VC_err.args[0]!r})
-                """).format(VC_err=VC_err, version=version)
-            sys.stderr.write(msg)
-            sys.exit(2)
-
-        # otherwise, reload ok
-        del pkg_resources, sys.modules['pkg_resources']
-        return _do_download(version, download_base, to_dir, download_delay)
-
-def _clean_check(cmd, target):
-    """
-    Run the command to download target. If the command fails, clean up before
-    re-raising the error.
-    """
-    try:
-        subprocess.check_call(cmd)
-    except subprocess.CalledProcessError:
-        if os.access(target, os.F_OK):
-            os.unlink(target)
-        raise
-
-def download_file_powershell(url, target):
-    """
-    Download the file at url to target using Powershell (which will validate
-    trust). Raise an exception if the command cannot complete.
-    """
-    target = os.path.abspath(target)
-    ps_cmd = (
-        "[System.Net.WebRequest]::DefaultWebProxy.Credentials = "
-        "[System.Net.CredentialCache]::DefaultCredentials; "
-        "(new-object System.Net.WebClient).DownloadFile(%(url)r, %(target)r)"
-        % vars()
-    )
-    cmd = [
-        'powershell',
-        '-Command',
-        ps_cmd,
-    ]
-    _clean_check(cmd, target)
-
-def has_powershell():
-    if platform.system() != 'Windows':
-        return False
-    cmd = ['powershell', '-Command', 'echo test']
-    with open(os.path.devnull, 'wb') as devnull:
-        try:
-            subprocess.check_call(cmd, stdout=devnull, stderr=devnull)
-        except Exception:
-            return False
-    return True
-
-download_file_powershell.viable = has_powershell
-
-def download_file_curl(url, target):
-    cmd = ['curl', url, '--silent', '--output', target]
-    _clean_check(cmd, target)
-
-def has_curl():
-    cmd = ['curl', '--version']
-    with open(os.path.devnull, 'wb') as devnull:
-        try:
-            subprocess.check_call(cmd, stdout=devnull, stderr=devnull)
-        except Exception:
-            return False
-    return True
-
-download_file_curl.viable = has_curl
-
-def download_file_wget(url, target):
-    cmd = ['wget', url, '--quiet', '--output-document', target]
-    _clean_check(cmd, target)
-
-def has_wget():
-    cmd = ['wget', '--version']
-    with open(os.path.devnull, 'wb') as devnull:
-        try:
-            subprocess.check_call(cmd, stdout=devnull, stderr=devnull)
-        except Exception:
-            return False
-    return True
-
-download_file_wget.viable = has_wget
-
-def download_file_insecure(url, target):
-    """
-    Use Python to download the file, even though it cannot authenticate the
-    connection.
-    """
-    src = urlopen(url)
-    try:
-        # Read all the data in one block.
-        data = src.read()
-    finally:
-        src.close()
-
-    # Write all the data in one block to avoid creating a partial file.
-    with open(target, "wb") as dst:
-        dst.write(data)
-
-download_file_insecure.viable = lambda: True
-
-def get_best_downloader():
-    downloaders = (
-        download_file_powershell,
-        download_file_curl,
-        download_file_wget,
-        download_file_insecure,
-    )
-    viable_downloaders = (dl for dl in downloaders if dl.viable())
-    return next(viable_downloaders, None)
-
-def download_setuptools(version=DEFAULT_VERSION, download_base=DEFAULT_URL,
-        to_dir=os.curdir, delay=15, downloader_factory=get_best_downloader):
-    """
-    Download setuptools from a specified location and return its filename
-
-    `version` should be a valid setuptools version number that is available
-    as an sdist for download under the `download_base` URL (which should end
-    with a '/'). `to_dir` is the directory where the egg will be downloaded.
-    `delay` is the number of seconds to pause before an actual download
-    attempt.
-
-    ``downloader_factory`` should be a function taking no arguments and
-    returning a function for downloading a URL to a target.
-    """
-    # making sure we use the absolute path
-    to_dir = os.path.abspath(to_dir)
-    zip_name = "setuptools-%s.zip" % version
-    url = download_base + zip_name
-    saveto = os.path.join(to_dir, zip_name)
-    if not os.path.exists(saveto):  # Avoid repeated downloads
-        log.warn("Downloading %s", url)
-        downloader = downloader_factory()
-        downloader(url, saveto)
-    return os.path.realpath(saveto)
-
-def _build_install_args(options):
-    """
-    Build the arguments to 'python setup.py install' on the setuptools package
-    """
-    return ['--user'] if options.user_install else []
-
-def _parse_args():
-    """
-    Parse the command line for options
-    """
-    parser = optparse.OptionParser()
-    parser.add_option(
-        '--user', dest='user_install', action='store_true', default=False,
-        help='install in user site package (requires Python 2.6 or later)')
-    parser.add_option(
-        '--download-base', dest='download_base', metavar="URL",
-        default=DEFAULT_URL,
-        help='alternative URL from where to download the setuptools package')
-    parser.add_option(
-        '--insecure', dest='downloader_factory', action='store_const',
-        const=lambda: download_file_insecure, default=get_best_downloader,
-        help='Use internal, non-validating downloader'
-    )
-    parser.add_option(
-        '--version', help="Specify which version to download",
-        default=DEFAULT_VERSION,
-    )
-    options, args = parser.parse_args()
-    # positional arguments are ignored
-    return options
-
-def main():
-    """Install or upgrade setuptools and EasyInstall"""
-    options = _parse_args()
-    archive = download_setuptools(
-        version=options.version,
-        download_base=options.download_base,
-        downloader_factory=options.downloader_factory,
-    )
-    return _install(archive, _build_install_args(options))
-
-if __name__ == '__main__':
-    sys.exit(main())
diff --git a/python/google/protobuf/internal/_parameterized.py b/python/google/protobuf/internal/_parameterized.py
index 6c5a2ba..3821b91 100755
--- a/python/google/protobuf/internal/_parameterized.py
+++ b/python/google/protobuf/internal/_parameterized.py
@@ -263,6 +263,8 @@
       'Cannot add parameters to %s,'
       ' which already has parameterized methods.' % (class_object,))
   class_object._id_suffix = id_suffix = {}
+  # We change the size of __dict__ while we iterate over it, 
+  # which Python 3.x will complain about, so use copy().
   for name, obj in class_object.__dict__.copy().items():
     if (name.startswith(unittest.TestLoader.testMethodPrefix)
         and isinstance(obj, types.FunctionType)):
diff --git a/python/setup.py b/python/setup.py
index 79e2369..23193cb 100755
--- a/python/setup.py
+++ b/python/setup.py
@@ -8,19 +8,7 @@
 
 # We must use setuptools, not distutils, because we need to use the
 # namespace_packages option for the "google" package.
-try:
-  from setuptools import setup, Extension, find_packages
-except ImportError:
-  try:
-    from ez_setup import use_setuptools
-    use_setuptools()
-    from setuptools import setup, Extension, find_packages
-  except ImportError:
-    sys.stderr.write(
-        "Could not import setuptools; make sure you have setuptools or "
-        "ez_setup installed.\n"
-    )
-    raise
+from setuptools import setup, Extension, find_packages
 
 from distutils.command.clean import clean as _clean
 
diff --git a/python/tox.ini b/python/tox.ini
index d73d27a..24b709e 100644
--- a/python/tox.ini
+++ b/python/tox.ini
@@ -1,5 +1,7 @@
 [tox]
 envlist =
+    # Py3 tests currently fail because of text handling issues,
+    # So only test py26/py27 for now.
     #py26,py27,py33,py34
     py26,py27