Define DEBUG in a separate module to resolve circular references.
diff --git a/Lib/distutils/debug.py b/Lib/distutils/debug.py
new file mode 100644
index 0000000..7ca76d6
--- /dev/null
+++ b/Lib/distutils/debug.py
@@ -0,0 +1,6 @@
+import os
+
+# If DISTUTILS_DEBUG is anything other than the empty string, we run in
+# debug mode.
+DEBUG = os.environ.get('DISTUTILS_DEBUG')
+