Latest wheel doesn't work with Python 2.6 on Travis CI

[Jun Omae]

​https://travis-ci.org/edgewall/trac/jobs/313949552#L208

Building wheels for collected packages: Genshi, configobj, lxml, twill, ordereddict
  Running setup.py bdist_wheel for Genshi ... error
  Complete output from command /Users/travis/venv-2.6/bin/python2.6 -u -c "import setuptools, tokenize;__file__='/private/var/folders/bb/n7t3rs157850byt_jfdcq9k80000gn/T/pip-build-m4N0rc/Genshi/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" bdist_wheel -d /var/folders/bb/n7t3rs157850byt_jfdcq9k80000gn/T/tmpDyj4gqpip-wheel- --python-tag cp26:
  /private/var/folders/bb/n7t3rs157850byt_jfdcq9k80000gn/T/pip-build-m4N0rc/Genshi/setup.py:72: DeprecationWarning: Features are deprecated and will be removed in a future version. See https://github.com/pypa/setuptools/issues/65.
    Extension('genshi._speedups', ['genshi/_speedups.c']),
  /System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/distutils/core.py:113: DeprecationWarning: Features are deprecated and will be removed in a future version. See https://github.com/pypa/setuptools/issues/65.
    _setup_distribution = dist = klass(attrs)
  Traceback (most recent call last):
    File "<string>", line 1, in <module>
    File "/private/var/folders/bb/n7t3rs157850byt_jfdcq9k80000gn/T/pip-build-m4N0rc/Genshi/setup.py", line 162, in <module>
      **extra
    File "/Users/travis/venv-2.6/lib/python2.6/site-packages/setuptools/__init__.py", line 129, in setup
      return distutils.core.setup(**attrs)
    File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/distutils/core.py", line 138, in setup
      ok = dist.parse_command_line()
    File "/Users/travis/venv-2.6/lib/python2.6/site-packages/setuptools/dist.py", line 439, in parse_command_line
      result = _Distribution.parse_command_line(self)
    File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/distutils/dist.py", line 460, in parse_command_line
      args = self._parse_command_opts(parser, args)
    File "/Users/travis/venv-2.6/lib/python2.6/site-packages/setuptools/dist.py", line 754, in _parse_command_opts
      nargs = _Distribution._parse_command_opts(self, parser, args)
    File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/distutils/dist.py", line 518, in _parse_command_opts
      cmd_class = self.get_command_class(command)
    File "/Users/travis/venv-2.6/lib/python2.6/site-packages/setuptools/dist.py", line 574, in get_command_class
      self.cmdclass[command] = cmdclass = ep.load()
    File "/Users/travis/venv-2.6/lib/python2.6/site-packages/pkg_resources/__init__.py", line 2422, in load
      return self.resolve()
    File "/Users/travis/venv-2.6/lib/python2.6/site-packages/pkg_resources/__init__.py", line 2428, in resolve
      module = __import__(self.module_name, fromlist=['__name__'], level=0)
    File "/Users/travis/venv-2.6/lib/python2.6/site-packages/wheel/bdist_wheel.py", line 407
      ignore=lambda x, y: {'PKG-INFO', 'requires.txt', 'SOURCES.txt',
                                     ^
  SyntaxError: invalid syntax

However, build doesn't stop.