Remove Python 2 support

Python 2 is long dead and devlib does not support it anymore, so cleanup
old Python 2-only code.

wa/utils/misc.py

@@ -41,10 +41,7 @@ from functools import reduce  # pylint: disable=redefined-builtin
 from operator import mul
 from tempfile import gettempdir, NamedTemporaryFile
 from time import sleep
-if sys.version_info[0] == 3:
-    from io import StringIO
-else:
-    from io import BytesIO as StringIO
+from io import StringIO
 # pylint: disable=wrong-import-position,unused-import
 from itertools import chain, cycle
 from distutils.spawn import find_executable  # pylint: disable=no-name-in-module, import-error

wa/utils/types.py

@@ -31,12 +31,8 @@ import numbers
 import shlex
 import sys
 from bisect import insort
-if sys.version_info[0] == 3:
-    from urllib.parse import quote, unquote  # pylint: disable=no-name-in-module, import-error
-    from past.builtins import basestring  # pylint: disable=redefined-builtin
-    long = int  # pylint: disable=redefined-builtin
-else:
-    from urllib import quote, unquote  # pylint: disable=no-name-in-module
+from urllib.parse import quote, unquote  # pylint: disable=no-name-in-module, import-error
+from past.builtins import basestring  # pylint: disable=redefined-builtin
 # pylint: disable=wrong-import-position
 from collections import defaultdict
 from collections.abc import MutableMapping
@@ -710,8 +706,6 @@ class ParameterDict(dict):
             prefix = 'f'
         elif isinstance(obj, bool):
             prefix = 'b'
-        elif isinstance(obj, long):
-            prefix = 'i'
         elif isinstance(obj, int):
             prefix = 'i'
         elif obj is None:
@@ -792,10 +786,7 @@ class ParameterDict(dict):
         return (key, self._decode(value))
 
     def iter_encoded_items(self):
-        if sys.version_info[0] == 3:
-            return dict.items(self)
-        else:
-            return dict.iteritems(self)
+        return dict.items(self)
 
     def get_encoded_value(self, name):
         return dict.__getitem__(self, name)