Remove usage of six library

... because now ldappool supports Python 3 only.

Change-Id: Ibeb60dbc81ef5b03f0732439ed07c2b672e78df5

ldappool/__init__.py

@@ -35,7 +35,6 @@
 # ***** END LICENSE BLOCK *****
 """ LDAP Connection Pool.
 """
-import codecs
 from contextlib import contextmanager
 import logging
 from threading import RLock
@@ -45,29 +44,26 @@ import ldap
 from ldap.ldapobject import ReconnectLDAPObject
 from prettytable import PrettyTable
 import re
-import six
-from six import PY2
 
 log = logging.getLogger(__name__)
-_utf8_encoder = codecs.getencoder('utf-8')
 
 
 def utf8_encode(value):
     """Encode a basestring to UTF-8.
 
-    If the string is unicode encode it to UTF-8, if the string is
-    str then assume it's already encoded. Otherwise raise a TypeError.
+    If the value is string, encode it to UTF-8, if the value is
+    bytes then assume it's already encoded. Otherwise raise a TypeError.
 
     :param value: A basestring
     :returns: UTF-8 encoded version of value
     :raises TypeError: If value is not basestring
     """
-    if isinstance(value, six.text_type):
-        return _utf8_encoder(value)[0]
-    elif isinstance(value, six.binary_type):
+    if isinstance(value, str):
+        return value.encode('utf-8')
+    elif isinstance(value, bytes):
         return value
     else:
-        raise TypeError("bytes or Unicode expected, got %s"
+        raise TypeError("bytes or str expected, got %s"
                         % type(value).__name__)
 
 
@@ -169,9 +165,6 @@ class ConnectionManager(object):
         return len(self._pool)
 
     def _match(self, bind, passwd):
-        if passwd is not None:
-            if PY2:
-                passwd = utf8_encode(passwd)
         with self._pool_lock:
             inactives = []
 
@@ -242,9 +235,6 @@ class ConnectionManager(object):
         :raises BackendError: If unable to connect to LDAP
         """
         connected = False
-        if passwd is not None:
-            if PY2:
-                passwd = utf8_encode(passwd)
 
         # If multiple server URIs have been provided, loop through
         # each one in turn in case of connection failures (server down,

requirements.txt

@@ -1,3 +1,2 @@
 python-ldap>=3.0.0 # PSF
 PrettyTable>=0.7.2
-six>=1.10.0 # MIT