Add support for SETUPTOOLS_DISABLE_VERSIONED_EASY_INSTALL_SCRIPT variable.

Support for old DISTRIBUTE_DISABLE_VERSIONED_EASY_INSTALL_SCRIPT variable is kept temporarily for backward compatibility.

setup.py

@@ -56,7 +56,8 @@ from setuptools.command.test import test as _test
 scripts = []
 
 console_scripts = ["easy_install = setuptools.command.easy_install:main"]
-if os.environ.get("DISTRIBUTE_DISABLE_VERSIONED_EASY_INSTALL_SCRIPT") is None:
+if os.environ.get("SETUPTOOLS_DISABLE_VERSIONED_EASY_INSTALL_SCRIPT") in (None, "", "0") and \
+    os.environ.get("DISTRIBUTE_DISABLE_VERSIONED_EASY_INSTALL_SCRIPT") in (None, "", "0"):
     console_scripts.append("easy_install-%s = setuptools.command.easy_install:main" % sys.version[:3])
 
 # specific command that is used to generate windows .exe files