Remove compatibility branch for Python 3.0-3.1.

pkg_resources/__init__.py

@@ -377,11 +377,7 @@ def get_build_platform():
     XXX Currently this is the same as ``distutils.util.get_platform()``, but it
     needs some hacks for Linux and Mac OS X.
     """
-    try:
-        # Python 2.7 or >=3.2
-        from sysconfig import get_platform
-    except ImportError:
-        from distutils.util import get_platform
+    from sysconfig import get_platform
 
     plat = get_platform()
     if sys.platform == "darwin" and not plat.startswith('macosx-'):