Remove dependency on six (#8650)

Fixes https://github.com/certbot/certbot/issues/8494.

I left the `six` dependency pinned in `tests/letstest/requirements.txt` and `tools/oldest_constraints.txt` because `six` is still a transitive dependency with our current pinnings.

The extra moving around of imports is due to me using `isort` to help me keep dependencies in sorted order after replacing imports of `six`.

* remove some six usage in acme

* remove six from acme

* remove six.add_metaclass usage

* fix six.moves.zip

* fix six.moves.builtins.open

* six.moves server fixes

* 's/six\.moves\.range/range/g'

* stop using six.moves.xrange

* fix urllib imports

* s/six\.binary_type/bytes/g

* s/six\.string_types/str/g

* 's/six\.text_type/str/g'

* fix six.iteritems usage

* fix itervalues usage

* switch from six.StringIO to io.StringIO

* remove six imports

* misc fixes

* stop using six.reload_module

* no six.PY2

* rip out six

* keep six pinned in oldest constraints

* fix log_test.py

* update changelog

certbot-nginx/certbot_nginx/_internal/nginxparser.py

@@ -15,7 +15,6 @@ from pyparsing import restOfLine
 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__)
@@ -79,7 +78,7 @@ class RawNginxDumper(object):
         """Iterates the dumped nginx content."""
         blocks = blocks or self.blocks
         for b0 in blocks:
-            if isinstance(b0, six.string_types):
+            if isinstance(b0, str):
                 yield b0
                 continue
             item = copy.deepcopy(b0)
@@ -96,7 +95,7 @@ class RawNginxDumper(object):
                 yield '}'
             else: # not a block - list of strings
                 semicolon = ";"
-                if isinstance(item[0], six.string_types) and item[0].strip() == '#': # comment
+                if isinstance(item[0], str) and item[0].strip() == '#': # comment
                     semicolon = ""
                 yield "".join(item) + semicolon
 
@@ -131,14 +130,14 @@ def load(_file):
 
 
 def dumps(blocks):
-    # type: (UnspacedList) -> six.text_type
+    # type: (UnspacedList) -> str
     """Dump to a Unicode string.
 
     :param UnspacedList block: The parsed tree
-    :rtype: six.text_type
+    :rtype: str
 
     """
-    return six.text_type(RawNginxDumper(blocks.spaced))
+    return str(RawNginxDumper(blocks.spaced))
 
 
 def dump(blocks, _file):
@@ -154,7 +153,7 @@ def dump(blocks, _file):
     _file.write(dumps(blocks))
 
 
-spacey = lambda x: (isinstance(x, six.string_types) and x.isspace()) or x == ''
+spacey = lambda x: (isinstance(x, str) and x.isspace()) or x == ''
 
 class UnspacedList(list):
     """Wrap a list [of lists], making any whitespace entries magically invisible"""

certbot-nginx/certbot_nginx/_internal/obj.py

@@ -1,7 +1,6 @@
 """Module contains classes used by the Nginx Configurator."""
 import re
 
-import six
 
 from certbot.plugins import common
 
@@ -211,7 +210,7 @@ class VirtualHost(object):
     def contains_list(self, test):
         """Determine if raw server block contains test list at top level
         """
-        for i in six.moves.range(0, len(self.raw) - len(test) + 1):
+        for i in range(0, len(self.raw) - len(test) + 1):
             if self.raw[i:i + len(test)] == test:
                 return True
         return False
@@ -250,7 +249,7 @@ def _find_directive(directives, directive_name, match_content=None):
     """Find a directive of type directive_name in directives. If match_content is given,
        Searches for `match_content` in the directive arguments.
     """
-    if not directives or isinstance(directives, six.string_types):
+    if not directives or isinstance(directives, str):
         return None
 
     # If match_content is None, just match on directive type. Otherwise, match on

certbot-nginx/certbot_nginx/_internal/parser.py

@@ -7,7 +7,6 @@ import logging
 import re
 
 import pyparsing
-import six
 
 from acme.magic_typing import Dict
 from acme.magic_typing import List
@@ -549,7 +548,7 @@ def _is_include_directive(entry):
     """
     return (isinstance(entry, list) and
             len(entry) == 2 and entry[0] == 'include' and
-            isinstance(entry[1], six.string_types))
+            isinstance(entry[1], str))
 
 def _is_ssl_on_directive(entry):
     """Checks if an nginx parsed entry is an 'ssl on' directive.
@@ -654,7 +653,7 @@ def _add_directive(block, directive, insert_at_top):
     directive_name = directive[0]
     def can_append(loc, dir_name):
         """ Can we append this directive to the block? """
-        return loc is None or (isinstance(dir_name, six.string_types)
+        return loc is None or (isinstance(dir_name, str)
             and dir_name in REPEATABLE_DIRECTIVES)
 
     err_fmt = 'tried to insert directive "{0}" but found conflicting "{1}".'

certbot-nginx/certbot_nginx/_internal/parser_obj.py

@@ -4,7 +4,6 @@ raw lists of tokens from pyparsing. """
 import abc
 import logging
 
-import six
 
 from acme.magic_typing import List
 from certbot import errors
@@ -152,7 +151,7 @@ class Statements(Parsable):
         if not isinstance(raw_list, list):
             raise errors.MisconfigurationError("Statements parsing expects a list!")
         # If there's a trailing whitespace in the list of statements, keep track of it.
-        if raw_list and isinstance(raw_list[-1], six.string_types) and raw_list[-1].isspace():
+        if raw_list and isinstance(raw_list[-1], str) and raw_list[-1].isspace():
             self._trailing_whitespace = raw_list[-1]
             raw_list = raw_list[:-1]
         self._data = [parse_raw(elem, self, add_spaces) for elem in raw_list]
@@ -184,7 +183,7 @@ class Statements(Parsable):
 def _space_list(list_):
     """ Inserts whitespace between adjacent non-whitespace tokens. """
     spaced_statement = [] # type: List[str]
-    for i in reversed(six.moves.xrange(len(list_))):
+    for i in reversed(range(len(list_))):
         spaced_statement.insert(0, list_[i])
         if i > 0 and not list_[i].isspace() and not list_[i-1].isspace():
             spaced_statement.insert(0, " ")
@@ -206,7 +205,7 @@ class Sentence(Parsable):
         :returns: whether this lists is parseable by `Sentence`.
         """
         return isinstance(lists, list) and len(lists) > 0 and \
-            all(isinstance(elem, six.string_types) for elem in lists)
+            all(isinstance(elem, str) for elem in lists)
 
     def parse(self, raw_list, add_spaces=False):
         """ Parses a list of string types into this object.
@@ -214,7 +213,7 @@ class Sentence(Parsable):
         if add_spaces:
             raw_list = _space_list(raw_list)
         if not isinstance(raw_list, list) or \
-                any(not isinstance(elem, six.string_types) for elem in raw_list):
+                any(not isinstance(elem, str) for elem in raw_list):
             raise errors.MisconfigurationError("Sentence parsing expects a list of string types.")
         self._data = raw_list