=== modified file 'Lib/pkgutil.py'
--- Lib/pkgutil.py	2013-04-14 21:45:56 +0000
+++ Lib/pkgutil.py	2013-04-18 23:46:36 +0000
@@ -66,6 +66,59 @@
     wrapper.register = register
     return wrapper
 
+def walk_path(path=None, *, pkg=None, onerror=None):
+    """Walk a package hierarchy, starting with the given path
+
+    Iterator producing (package, subpackages, submodules) triples. The first
+    entry is the package currently being walked, or None for the top level path.
+    The subpackages and submodules entries are dictionaries mapping from fully
+    qualified module names to the appropriate module loaders.
+
+    Entries may be removed from the subpackages dictionary to avoid loading
+    those packages and recursing into them.
+
+    If both pkg and path are None, walks sys.path
+
+    If path is not None, walks the specified path.
+
+    If pkg is not None, walks pkg.__path__
+
+    Providing both path and pkg results in ValueError
+    """
+    if path is not None and pkg is not None:
+        raise ValueError("Cannot specify both path and pkg")
+
+    if pkg is not None:
+        path = pkg.__path__
+    if path is None:
+        path = sys.path
+
+    subpkgs = {}
+    submods = {}
+    prefix = "" if pkg is None else pkg.__name__ + "."
+
+    for importer, name, ispkg in iter_modules(path, prefix):
+        if ispkg:
+            subpkgs[name] = importer
+        else:
+            submods[name] = importer
+
+    yield pkg, subpkgs, submods
+
+    for name in subpkgs:
+        try:
+            __import__(name)
+        except ImportError:
+            if onerror is not None:
+                onerror(name)
+        except Exception:
+            if onerror is not None:
+                onerror(name)
+            else:
+                raise
+        else:
+            pkg = sys.modules[name]
+            yield from walk_path(pkg=pkg)
 
 def walk_packages(path=None, prefix='', onerror=None):
     """Yields (module_loader, name, ispkg) for all modules recursively