Index: Lib/os.py
===================================================================
--- Lib/os.py	(révision 66781)
+++ Lib/os.py	(copie de travail)
@@ -358,6 +358,9 @@
     PATH = envpath.split(pathsep)
     last_exc = saved_exc = None
     saved_tb = None
+    if isinstance(file, bytes):
+        encoding = sys.getfilesystemencoding()
+        PATH = (bytes(dir, encoding) for dir in PATH)
     for dir in PATH:
         fullname = path.join(dir, file)
         try: