Switch to setuptools alone. Work around pypa/setuptools#456.

.pylintrc

@@ -675,7 +675,8 @@ allowed-3rd-party-modules=msgpack,
                           libcloud,
                           zmq,
                           pytest,
-                          pytestsalt
+                          pytestsalt,
+                          setuptools
 
 
 [EXCEPTIONS]

setup.py

@@ -5,7 +5,7 @@ The setup script for salt
 '''
 
 # pylint: disable=file-perms,ungrouped-imports,wrong-import-order,wrong-import-position,repr-flag-used-in-string
-# pylint: disable=3rd-party-local-module-not-gated,resource-leakage
+# pylint: disable=3rd-party-local-module-not-gated,resource-leakage,blacklisted-module
 # pylint: disable=C0111,E1101,E1103,F0401,W0611,W0201,W0232,R0201,R0902,R0903
 
 # For Python 2.5.  A no-op on 2.6 and above.
@@ -14,6 +14,7 @@ from __future__ import absolute_import, print_function, with_statement
 import os
 import sys
 import glob
+import inspect
 import operator
 import platform
 try:
@@ -22,16 +23,21 @@ except ImportError:
     from urllib.request import urlopen  # pylint: disable=no-name-in-module
 from datetime import datetime
 # pylint: disable=E0611
+import setuptools
 import distutils.dist
 from distutils import log
 from distutils.cmd import Command
 from distutils.errors import DistutilsArgError
 from distutils.command.build import build
 from distutils.command.clean import clean
-from distutils.command.sdist import sdist
 from distutils.command.install_lib import install_lib
 from distutils.version import LooseVersion  # pylint: disable=blacklisted-module
 from ctypes.util import find_library
+from setuptools import setup
+from setuptools.command.develop import develop
+from setuptools.command.install import install
+from setuptools.command.sdist import sdist
+from setuptools.command.egg_info import egg_info
 # pylint: enable=E0611
 
 try:
@@ -78,36 +84,6 @@ else:
 # Store a reference whether if we're running under Python 3 and above
 IS_PY3 = sys.version_info > (3,)
 
-# Use setuptools only if the user opts-in by setting the USE_SETUPTOOLS env var
-# Or if setuptools was previously imported (which is the case when using
-# 'distribute')
-# This ensures consistent behavior but allows for advanced usage with
-# virtualenv, buildout, and others.
-WITH_SETUPTOOLS = False
-if 'USE_SETUPTOOLS' in os.environ or 'setuptools' in sys.modules:
-    try:
-        from setuptools import setup
-        from setuptools.command.develop import develop
-        from setuptools.command.install import install
-        from setuptools.command.sdist import sdist
-        from setuptools.command.egg_info import egg_info
-        WITH_SETUPTOOLS = True
-    except ImportError:
-        WITH_SETUPTOOLS = False
-
-if WITH_SETUPTOOLS is False:
-    import warnings
-    # pylint: disable=E0611
-    from distutils.command.install import install
-    from distutils.core import setup
-    # pylint: enable=E0611
-    warnings.filterwarnings(
-        'ignore',
-        'Unknown distribution option: \'(extras_require|tests_require|install_requires|zip_safe)\'',
-        UserWarning,
-        'distutils.dist'
-    )
-
 try:
     # Add the esky bdist target if the module is available
     # may require additional modules depending on platform
@@ -345,7 +321,6 @@ class WriteSaltSshPackagingFile(Command):
             # pylint: enable=E0602
 
 
-if WITH_SETUPTOOLS:
 class Develop(develop):
     user_options = develop.user_options + [
         ('write-salt-version', None,
@@ -724,6 +699,15 @@ class Install(install):
         install.finalize_options(self)
 
     def run(self):
+        from distutils.version import StrictVersion
+        if StrictVersion(setuptools.__version__) < StrictVersion('9.1'):
+            sys.stderr.write(
+                '\n\nInstalling Salt requires setuptools >= 9.1\n'
+                'Available setuptools version is {}\n\n'.format(setuptools.__version__)
+            )
+            sys.stderr.flush()
+            sys.exit(1)
+
         # Let's set the running_salt_install attribute so we can add
         # _version.py in the build command
         self.distribution.running_salt_install = True
@@ -738,6 +722,38 @@ class Install(install):
         # Run install.run
         install.run(self)
 
+    @staticmethod
+    def _called_from_setup(run_frame):
+        """
+        Attempt to detect whether run() was called from setup() or by another
+        command.  If called by setup(), the parent caller will be the
+        'run_command' method in 'distutils.dist', and *its* caller will be
+        the 'run_commands' method.  If called any other way, the
+        immediate caller *might* be 'run_command', but it won't have been
+        called by 'run_commands'. Return True in that case or if a call stack
+        is unavailable. Return False otherwise.
+        """
+        if run_frame is None:
+            # If run_frame is None, just call the parent class logic
+            return install._called_from_setup(run_frame)
+
+        # Because Salt subclasses the setuptools install command, it needs to
+        # override this static method to provide the right frame for the logic
+        # so apply.
+
+        # We first try the current run_frame in case the issue
+        # https://github.com/pypa/setuptools/issues/456 is fixed.
+        first_call = install._called_from_setup(run_frame)
+        if first_call:
+            return True
+
+        # Fallback to providing the parent frame to have the right logic kick in
+        second_call = install._called_from_setup(run_frame.f_back)
+        if second_call is None:
+            # There was no parent frame?!
+            return first_call
+        return second_call
+
 
 class InstallLib(install_lib):
     def run(self):
@@ -875,6 +891,7 @@ class SaltDistribution(distutils.dist.Distribution):
                               'build': Build,
                               'sdist': Sdist,
                               'install': Install,
+                              'develop': Develop,
                               'write_salt_version': WriteSaltVersion,
                               'generate_salt_syspaths': GenerateSaltSyspaths,
                               'write_salt_ssh_packaging_file': WriteSaltSshPackagingFile})
@@ -884,9 +901,6 @@ class SaltDistribution(distutils.dist.Distribution):
         if IS_WINDOWS_PLATFORM:
             self.cmdclass.update({'download-windows-dlls': DownloadWindowsDlls})
 
-        if WITH_SETUPTOOLS:
-            self.cmdclass.update({'develop': Develop})
-
         self.license = 'Apache Software License 2.0'
         self.packages = self.discover_packages()
         self.zip_safe = False