nginx: fix Unicode crash on Python 2 (#8480)

* nginx: fix py2 unicode sandwich

The nginx parser would crash when saving configuraitons containing
Unicode, because py2's `str` type does not support Unicode.

This change fixes that crash by ensuring that a string type supporting
Unicode is used in both Python 2 and Python 3.

* nginx: add unicode to the integration test config

* update CHANGELOG

certbot-nginx/certbot_nginx/_internal/http_01.py

@@ -1,5 +1,6 @@
 """A class that performs HTTP-01 challenges for Nginx"""
 
+import io
 import logging
 
 from acme import challenges
@@ -102,7 +103,7 @@ class NginxHttp01(common.ChallengePerformer):
         self.configurator.reverter.register_file_creation(
             True, self.challenge_conf)
 
-        with open(self.challenge_conf, "w") as new_conf:
+        with io.open(self.challenge_conf, "w", encoding="utf-8") as new_conf:
             nginxparser.dump(config, new_conf)
 
     def _default_listen_addresses(self):

certbot-nginx/certbot_nginx/_internal/nginxparser.py

@@ -16,6 +16,7 @@ from pyparsing import stringEnd
 from pyparsing import White
 from pyparsing import ZeroOrMore
 import six
+from acme.magic_typing import IO, Any # pylint: disable=unused-import
 
 logger = logging.getLogger(__name__)
 
@@ -130,26 +131,27 @@ def load(_file):
 
 
 def dumps(blocks):
-    """Dump to a string.
+    # type: (UnspacedList) -> six.text_type
+    """Dump to a Unicode string.
 
     :param UnspacedList block: The parsed tree
-    :param int indentation: The number of spaces to indent
-    :rtype: str
+    :rtype: six.text_type
 
     """
-    return str(RawNginxDumper(blocks.spaced))
+    return six.text_type(RawNginxDumper(blocks.spaced))
 
 
 def dump(blocks, _file):
+    # type: (UnspacedList, IO[Any]) -> None
     """Dump to a file.
 
     :param UnspacedList block: The parsed tree
-    :param file _file: The file to dump to
-    :param int indentation: The number of spaces to indent
-    :rtype: NoneType
+    :param IO[Any] _file: The file stream to dump to. It must be opened with
+                          Unicode encoding.
+    :rtype: None
 
     """
-    return _file.write(dumps(blocks))
+    _file.write(dumps(blocks))
 
 
 spacey = lambda x: (isinstance(x, six.string_types) and x.isspace()) or x == ''

certbot-nginx/certbot_nginx/_internal/parser.py

@@ -249,7 +249,7 @@ class NginxParser(object):
                     continue
                 out = nginxparser.dumps(tree)
                 logger.debug('Writing nginx conf tree to %s:\n%s', filename, out)
-                with open(filename, 'w') as _file:
+                with io.open(filename, 'w', encoding='utf-8') as _file:
                     _file.write(out)
 
             except IOError: