Index: Lib/os.py
===================================================================
--- Lib/os.py	(révision 80421)
+++ Lib/os.py	(copie de travail)
@@ -355,6 +355,8 @@
         return
     last_exc = saved_exc = None
     saved_tb = None
+    if isinstance(file, bytes):
+        file = file.decode(sys.getfilesystemencoding(), 'surrogateescape')
     for dir in get_exec_path(env):
         fullname = path.join(dir, file)
         try:
@@ -380,7 +382,13 @@
     """
     if env is None:
         env = environ
-    return env.get('PATH', defpath).split(pathsep)
+    if 'PATH' in env:
+        path = env['PATH']
+        if isinstance(path, bytes):
+            path = path.decode(sys.getfilesystemencoding(), 'surrogateescape')
+    else:
+        path = defpath
+    return path.split(pathsep)
 
 
 # Change environ to automatically call putenv(), unsetenv if they exist.
Index: Lib/test/test_subprocess.py
===================================================================
--- Lib/test/test_subprocess.py	(révision 80424)
+++ Lib/test/test_subprocess.py	(copie de travail)
@@ -827,7 +827,21 @@
             stdout = stdout.rstrip(b'\n\r')
             self.assertEquals(stdout, value_repr)
 
+    def fs_encode(self, filename):
+        return filename.encode(sys.getfilesystemencoding(), "surrogateescape")
 
+    def test_bytes_program(self):
+        path, program = os.path.split(sys.executable)
+        path = self.fs_encode(path)
+        program = self.fs_encode(program)
+        env = os.environ.copy()
+        env["PATH"] = path
+        exitcode = subprocess.call(
+            [program, "-c", "pass"],
+            env=env)
+        self.assertEquals(exitcode, 0)
+
+
 @unittest.skipUnless(mswindows, "Windows specific tests")
 class Win32ProcessTestCase(BaseTestCase):
 
Index: Lib/subprocess.py
===================================================================
--- Lib/subprocess.py	(révision 80421)
+++ Lib/subprocess.py	(copie de travail)
@@ -1088,6 +1088,11 @@
 
                     if _posixsubprocess:
                         fs_encoding = sys.getfilesystemencoding()
+                        def fs_decode(s):
+                            if isinstance(s, str):
+                                return s
+                            else:
+                                return s.decode(fs_encoding, 'surrogateescape')
                         def fs_encode(s):
                             """Encode s for use in the env, fs or cmdline."""
                             if isinstance(s, bytes):
@@ -1110,7 +1115,8 @@
                         else:
                             # This matches the behavior of os._execvpe().
                             path_list = os.get_exec_path(env)
-                            executable_list = (os.path.join(dir, executable)
+                            executable_str = fs_decode(executable)
+                            executable_list = (os.path.join(dir, executable_str)
                                                for dir in path_list)
                             executable_list = tuple(fs_encode(exe)
                                                     for exe in executable_list)