Use distutils.debug.DEBUG instead of distutils.core.DEBUG.

Note that distutils.core.DEBUG still works if client code uses it, but
the core code avoids circular references by using distutils.debug.
diff --git a/Lib/distutils/ccompiler.py b/Lib/distutils/ccompiler.py
index f1a50cb..5a0641e 100644
--- a/Lib/distutils/ccompiler.py
+++ b/Lib/distutils/ccompiler.py
@@ -923,7 +923,7 @@
         log.debug(msg)
 
     def debug_print (self, msg):
-        from distutils.core import DEBUG
+        from distutils.debug import DEBUG
         if DEBUG:
             print msg
 
diff --git a/Lib/distutils/cmd.py b/Lib/distutils/cmd.py
index 25ff302..6a26818 100644
--- a/Lib/distutils/cmd.py
+++ b/Lib/distutils/cmd.py
@@ -198,7 +198,7 @@
         """Print 'msg' to stdout if the global DEBUG (taken from the
         DISTUTILS_DEBUG environment variable) flag is true.
         """
-        from distutils.core import DEBUG
+        from distutils.debug import DEBUG
         if DEBUG:
             print msg
             sys.stdout.flush()
diff --git a/Lib/distutils/command/bdist_rpm.py b/Lib/distutils/command/bdist_rpm.py
index dd9dc66..bbaad7d 100644
--- a/Lib/distutils/command/bdist_rpm.py
+++ b/Lib/distutils/command/bdist_rpm.py
@@ -10,7 +10,8 @@
 import sys, os, string
 import glob
 from types import *
-from distutils.core import Command, DEBUG
+from distutils.core import Command
+from distutils.debug import DEBUG
 from distutils.util import get_platform
 from distutils.file_util import write_file
 from distutils.errors import *
diff --git a/Lib/distutils/command/install.py b/Lib/distutils/command/install.py
index 322177f..67f3789 100644
--- a/Lib/distutils/command/install.py
+++ b/Lib/distutils/command/install.py
@@ -10,7 +10,8 @@
 
 import sys, os, string
 from types import *
-from distutils.core import Command, DEBUG
+from distutils.core import Command
+from distutils.debug import DEBUG
 from distutils.sysconfig import get_config_vars
 from distutils.errors import DistutilsPlatformError
 from distutils.file_util import write_file
diff --git a/Lib/distutils/core.py b/Lib/distutils/core.py
index 8a348ce..9a6bff6 100644
--- a/Lib/distutils/core.py
+++ b/Lib/distutils/core.py
@@ -13,10 +13,7 @@
 import sys, os
 from types import *
 
-# If DISTUTILS_DEBUG is anything other than the empty string, we run in
-# debug mode.
-DEBUG = os.environ.get('DISTUTILS_DEBUG')
-
+from distutils.debug import DEBUG
 from distutils.errors import *
 from distutils.util import grok_environment_error
 
@@ -25,7 +22,6 @@
 from distutils.cmd import Command
 from distutils.extension import Extension
 
-
 # This is a barebones help message generated displayed when the user
 # runs the setup script with no arguments at all.  More useful help
 # is generated with various --help options: global help, list commands,
diff --git a/Lib/distutils/dist.py b/Lib/distutils/dist.py
index f995d58..92cb832 100644
--- a/Lib/distutils/dist.py
+++ b/Lib/distutils/dist.py
@@ -16,7 +16,7 @@
 from distutils.fancy_getopt import FancyGetopt, translate_longopt
 from distutils.util import check_environ, strtobool, rfc822_escape
 from distutils import log
-from distutils.core import DEBUG
+from distutils.debug import DEBUG
 
 # Regex to define acceptable Distutils command names.  This is not *quite*
 # the same as a Python NAME -- I don't allow leading underscores.  The fact
diff --git a/Lib/distutils/filelist.py b/Lib/distutils/filelist.py
index e2e2457..b4f3269 100644
--- a/Lib/distutils/filelist.py
+++ b/Lib/distutils/filelist.py
@@ -54,7 +54,7 @@
         """Print 'msg' to stdout if the global DEBUG (taken from the
         DISTUTILS_DEBUG environment variable) flag is true.
         """
-        from distutils.core import DEBUG
+        from distutils.debug import DEBUG
         if DEBUG:
             print msg