Kill support for python 2.6.

Closes pex-tool#405

.travis.yml

@@ -16,10 +16,6 @@ matrix:
       python: "2.7"
       env: TOXENV=isort-check
 
-    - language: python
-      python: "2.6"
-      env: TOXENV=py26
-
     - language: python
       python: "2.7"
       env: TOXENV=py27

docs/buildingpex.rst

@@ -37,8 +37,8 @@ and invoke it.  When no entry point is specified, "invocation" means starting an
 .. code-block:: bash
 
     $ pex
-    Python 2.6.9 (unknown, Jan  2 2014, 14:52:48)
-    [GCC 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2336.11.00)] on darwin
+    Python 3.6.2 (default, Jul 20 2017, 03:52:27)
+    [GCC 7.1.1 20170630] on linux
     Type "help", "copyright", "credits" or "license" for more information.
     (InteractiveConsole)
     >>>
@@ -51,16 +51,24 @@ absolute path of a Python binary or the name of a Python interpreter within the
 
 .. code-block:: bash
 
-    $ pex --python=python3.3
-    Python 3.3.3 (default, Jan  2 2014, 14:57:01)
-    [GCC 4.2.1 Compatible Apple Clang 4.0 ((tags/Apple/clang-421.0.60))] on darwin
+    $ pex
+    Python 3.6.2 (default, Jul 20 2017, 03:52:27)
+    [GCC 7.1.1 20170630] on linux
     Type "help", "copyright", "credits" or "license" for more information.
     (InteractiveConsole)
-    >>> print "this won't work!"
+    >>> print "This won't work!"
       File "<console>", line 1
-        print "this won't work!"
+        print "This won't work!"
                                ^
-    SyntaxError: invalid syntax
+    SyntaxError: Missing parentheses in call to 'print'
+    >>>
+    $ pex --python=python2.7
+    Python 2.7.13 (default, Jul 21 2017, 03:24:34)
+    [GCC 7.1.1 20170630] on linux2
+    Type "help", "copyright", "credits" or "license" for more information.
+    (InteractiveConsole)
+    >>> print "This works."
+    This works.
 
 
 Specifying requirements
@@ -74,8 +82,8 @@ and ``psutil>1``:
 .. code-block:: bash
 
     $ pex flask 'psutil>1'
-    Python 2.6.9 (unknown, Jan  2 2014, 14:52:48)
-    [GCC 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2336.11.00)] on darwin
+    Python 3.6.2 (default, Jul 20 2017, 03:52:27)
+    [GCC 7.1.1 20170630] on linux
     Type "help", "copyright", "credits" or "license" for more information.
     (InteractiveConsole)
     >>>

pex/compatibility.py

@@ -6,23 +6,10 @@
 
 import os
 from abc import ABCMeta
+from io import BytesIO, StringIO
 from numbers import Integral, Real
 from sys import version_info as sys_version_info
 
-# TODO(wickman)  Since the io package is available in 2.6.x, use that instead of
-# cStringIO/StringIO
-try:
-  # CPython 2.x
-  from cStringIO import StringIO
-except ImportError:
-  try:
-    # Python 2.x
-    from StringIO import StringIO
-  except:
-    # Python 3.x
-    from io import StringIO
-    from io import BytesIO
-
 try:
   # Python 2.x
   from ConfigParser import ConfigParser

pex/http.py

@@ -37,11 +37,12 @@
 else:
   import urllib2 as urllib_request
 
-# This is available as hashlib.algorithms_guaranteed in >=3.2 and as
-# hashlib.algorithms in >=2.7, but not available in 2.6, so we enumerate
-# here.
-HASHLIB_ALGORITHMS = frozenset(['md5', 'sha1', 'sha224', 'sha256', 'sha384', 'sha512'])
-
+try:
+  # The hashlib.algorithms_guaranteed function is available in >=2.7.9 and >=3.2.
+  HASHLIB_ALGORITHMS = frozenset(hashlib.algorithms_guaranteed)
+except AttributeError:
+  # And the hashlib.algorithms function covers the rest of the 2.7 versions we support.
+  HASHLIB_ALGORITHMS = frozenset(hashlib.algorithms)
 
 class Context(AbstractClass):
   """Encapsulate the networking necessary to do requirement resolution.

pex/interpreter.py

@@ -155,7 +155,7 @@ def hashbang(self):
   @property
   def python(self):
     # return the python version in the format of the 'python' key for distributions
-    # specifically, '2.6', '2.7', '3.2', etc.
+    # specifically, '2.7', '3.2', etc.
     return '%d.%d' % (self.version[0:2])
 
   def __str__(self):
@@ -328,7 +328,7 @@ def version_filter(version):
   @classmethod
   def sanitized_environment(cls):
     # N.B. This is merely a hack because sysconfig.py on the default OS X
-    # installation of 2.6/2.7 breaks.
+    # installation of 2.7 breaks.
     env_copy = os.environ.copy()
     env_copy.pop('MACOSX_DEPLOYMENT_TARGET', None)
     return env_copy
@@ -400,10 +400,6 @@ def get_location(self, req):
       if req.key == dist_name and dist_version in req:
         return location
 
-  def supports_wheel_install(self):
-    """Wheel installs are broken in python 2.6"""
-    return self.version >= (2, 7)
-
   def __hash__(self):
     return hash((self._binary, self._identity))
 

pex/pep425.py

@@ -92,7 +92,7 @@ def _iter_supported_tags(cls, impl, version, platform):
     """Given a set of tags, iterate over supported tags.
 
     :param impl: Python implementation tag e.g. cp, jy, pp.
-    :param version: E.g. '26', '33'
+    :param version: E.g. '27', '33'
     :param platform: Platform as from :function:`pkg_resources.get_supported_platform`,
     for example 'linux-x86_64' or 'macosx-10.4-x86_64'.
     :returns: Iterator over (pyver, abi, platform) tuples.

pex/pex_builder.py

@@ -271,11 +271,7 @@ def _add_dist_zip(self, path, dist_name):
     # But wheels don't have to be importable, so we need to force them
     # into an importable shape. We can do that by installing it into its own
     # wheel dir.
-    if not self.interpreter.supports_wheel_install():
-      self._logger.warn("Wheel dependency on %s may not work correctly with Python 2.6." %
-                        dist_name)
-
-    if self.interpreter.supports_wheel_install() and dist_name.endswith("whl"):
+    if dist_name.endswith("whl"):
       from wheel.install import WheelFile
       tmp = safe_mkdtemp()
       whltmp = os.path.join(tmp, dist_name)

setup.py

@@ -40,12 +40,12 @@
     'Operating System :: MacOS :: MacOS X',
     'Programming Language :: Python',
     'Programming Language :: Python :: 2',
-    'Programming Language :: Python :: 2.6',
     'Programming Language :: Python :: 2.7',
     'Programming Language :: Python :: 3',
     'Programming Language :: Python :: 3.3',
     'Programming Language :: Python :: 3.4',
     'Programming Language :: Python :: 3.5',
+    'Programming Language :: Python :: 3.6',
   ],
   packages = [
     'pex',

tests/test_pex.py

@@ -186,8 +186,6 @@ def test_site_libs_excludes_prefix():
     assert sys.prefix not in site_libs
 
 
-@pytest.mark.skipif(sys.version_info < (2, 7),
-                    reason="wheel script installation is broken on python 2.6")
 @pytest.mark.parametrize('zip_safe', (False, True))
 @pytest.mark.parametrize('project_name', ('my_project', 'my-project'))
 @pytest.mark.parametrize('installer_impl', (EggInstaller, WheelInstaller))

tests/test_pex_builder.py

@@ -68,8 +68,6 @@ def test_pex_builder():
       assert fp.read() == 'success'
 
 
-@pytest.mark.skipif(sys.version_info < (2, 7),
-                    reason="wheel script installation is broken on python 2.6")
 def test_pex_builder_wheeldep():
   """Repeat the pex_builder test, but this time include an import of
   something from a wheel that doesn't come in importable form.

tox.ini

@@ -17,7 +17,6 @@ deps =
     twitter.common.testing>=0.3.1,<0.4.0
     wheel==0.29.0
     packaging==16.8
-    py26: mock
     py27: mock
     pypy: mock
     run: requests
@@ -135,9 +134,6 @@ commands = pex --cache-dir {envtmpdir}/buildcache wheel requests . -o dist/pex35
 commands = pex --cache-dir {envtmpdir}/buildcache wheel requests . -o dist/pex36 -e pex.bin.pex:main -v
 
 # Would love if you didn't have to enumerate environments here :-\
-[testenv:py26]
-[testenv:py26-requests]
-[testenv:py26-requests-cachecontrol]
 [testenv:py27]
 [testenv:py27-requests]
 [testenv:py27-requests-cachecontrol]