[BUG] fail to build tox using Python2

[stanislavlevin]

I'm building tox in Hasher environment ( https://en.altlinux.org/Hasher ).
Since 3.8.0 python2 build fails with:

python setup.py build -v
Traceback (most recent call last):
  File "setup.py", line 18, in <module>
    package_dir={"": "src"},
  File "/usr/lib/python2.7/site-packages/setuptools/__init__.py", line 144, in setup
    _install_setup_requires(attrs)
  File "/usr/lib/python2.7/site-packages/setuptools/__init__.py", line 137, in _install_setup_requires
    dist.parse_config_files(ignore_option_errors=True)
  File "/usr/lib/python2.7/site-packages/setuptools/dist.py", line 703, in parse_config_files
    self._parse_config_files(filenames=filenames)
  File "/usr/lib/python2.7/site-packages/setuptools/dist.py", line 600, in _parse_config_files
    (parser.read_file if six.PY3 else parser.readfp)(reader)
  File "/usr/lib64/python2.7/ConfigParser.py", line 324, in readfp
    self._read(fp, filename)
  File "/usr/lib64/python2.7/ConfigParser.py", line 479, in _read
    line = fp.readline()
  File "/usr/lib64/python2.7/encodings/ascii.py", line 26, in decode
    return codecs.ascii_decode(input, self.errors)[0]
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 345: ordinal not in range(128)

python -c "import setuptools;print setuptools.__version__"
40.8.0

locale
LANG=
LC_CTYPE="POSIX"
LC_NUMERIC="POSIX"
LC_TIME="POSIX"
LC_COLLATE="POSIX"
LC_MONETARY="POSIX"
LC_MESSAGES="POSIX"
LC_PAPER="POSIX"
LC_NAME="POSIX"
LC_ADDRESS="POSIX"
LC_TELEPHONE="POSIX"
LC_MEASUREMENT="POSIX"
LC_IDENTIFICATION="POSIX"
LC_ALL=

Python3 build is OK.