Fix setup.py to resolve numpy requirement

during pre-install. This should allow
'pip install numpy cython scipy scikit-learn'
to install scikit.

This fix is based of issue and fixes in Scipy:
scipy/scipy#453
branden/scipy@ad0dd3e

Author: abh1j337

setup.py

@@ -31,6 +31,7 @@
 # We can actually import a restricted version of sklearn that
 # does not need the compiled code
 import sklearn
+
 VERSION = sklearn.__version__
 
 ###############################################################################
@@ -45,14 +46,12 @@
             )).intersection(sys.argv)) > 0:
     import setuptools
     extra_setuptools_args = dict(
-            zip_safe=False,  # the package can run out of an .egg file
-            include_package_data=True,
-        )
+        zip_safe=False,  # the package can run out of an .egg file
+        include_package_data=True,
+    )
 else:
     extra_setuptools_args = dict()
 
-###############################################################################
-from numpy.distutils.core import setup
 
 def configuration(parent_package='', top_path=None):
     if os.path.exists('MANIFEST'):
@@ -73,29 +72,50 @@ def configuration(parent_package='', top_path=None):
     return config
 
 
-if __name__ == "__main__":
+def setup_package():
+    metadata = dict(name=DISTNAME,
+                    maintainer=MAINTAINER,
+                    maintainer_email=MAINTAINER_EMAIL,
+                    description=DESCRIPTION,
+                    license=LICENSE,
+                    url=URL,
+                    version=VERSION,
+                    download_url=DOWNLOAD_URL,
+                    long_description=LONG_DESCRIPTION,
+                    classifiers=['Intended Audience :: Science/Research',
+                                 'Intended Audience :: Developers',
+                                 'License :: OSI Approved',
+                                 'Programming Language :: C',
+                                 'Programming Language :: Python',
+                                 'Topic :: Software Development',
+                                 'Topic :: Scientific/Engineering',
+                                 'Operating System :: Microsoft :: Windows',
+                                 'Operating System :: POSIX',
+                                 'Operating System :: Unix',
+                                 'Operating System :: MacOS'],
+                    **extra_setuptools_args)
+
+    if len(sys.argv) >= 2 and ('--help' in sys.argv[1:] or sys.argv[1]
+       in ('--help-commands', 'egg_info', '--version', 'clean')):
+
+        # For these actions, NumPy is not required.
+        #
+        # They are required to succeed without Numpy for example when
+        # pip is used to install Scikit when Numpy is not yet present in
+        # the system.
+        try:
+            from setuptools import setup
+        except ImportError:
+            from distutils.core import setup
+
+        metadata['version'] = VERSION
+    else:
+        from numpy.distutils.core import setup
+
+        metadata['configuration'] = configuration
+
+    setup(**metadata)
 
-    setup(configuration=configuration,
-          name=DISTNAME,
-          maintainer=MAINTAINER,
-          maintainer_email=MAINTAINER_EMAIL,
-          description=DESCRIPTION,
-          license=LICENSE,
-          url=URL,
-          version=VERSION,
-          download_url=DOWNLOAD_URL,
-          long_description=LONG_DESCRIPTION,
-          classifiers=[
-              'Intended Audience :: Science/Research',
-              'Intended Audience :: Developers',
-              'License :: OSI Approved',
-              'Programming Language :: C',
-              'Programming Language :: Python',
-              'Topic :: Software Development',
-              'Topic :: Scientific/Engineering',
-              'Operating System :: Microsoft :: Windows',
-              'Operating System :: POSIX',
-              'Operating System :: Unix',
-              'Operating System :: MacOS'
-             ],
-      **extra_setuptools_args)
+
+if __name__ == "__main__":
+    setup_package()