The new packaging module should not use the locale encoding

Lib/packaging/tests/support.py

 """Support code for packaging test cases.
 
 A few helper classes are provided: LoggingCatcher, TempdirManager and
 EnvironRestorer. They are written to be used as mixins::
 
     from packaging.tests import unittest
     from packaging.tests.support import LoggingCatcher
 
     class SomeTestCase(LoggingCatcher, unittest.TestCase):
 
@@ skipping 128 matching lines @@
         return d
 
     def write_file(self, path, content='xxx'):
         """Write a file at the given path.
 
         path can be a string, a tuple or a list; if it's a tuple or list,
         os.path.join will be used to produce a path.
         """
         if isinstance(path, (list, tuple)):
             path = os.path.join(*path)
-        f = open(path, 'w')
+        f = open(path, 'w', encoding='utf8')
         try:
             f.write(content)
         finally:
             f.close()
 
     def create_dist(self, **kw):
         """Create a stub distribution object and files.
 
         This function creates a Distribution instance (use keyword arguments
         to customize it) and a temporary directory with a project structure
@@ skipping 90 matching lines @@
     d.parse_config_files()
     d.parse_command_line()
     return d
 
 
 try:
     from test.support import skip_unless_symlink
 except ImportError:
     skip_unless_symlink = unittest.skip(
         'requires test.support.skip_unless_symlink')