Index: Doc/library/os.rst
===================================================================
--- Doc/library/os.rst	(révision 81236)
+++ Doc/library/os.rst	(copie de travail)
@@ -142,7 +142,7 @@
    synchronized (modify :data:`environb` updates :data:`environ`, and vice
    versa).
 
-   Availability: Unix.
+   :data:`environb` is available if :data:`supports_bytes_environ` is True.
 
    .. versionadded:: 3.2
 
@@ -457,6 +457,12 @@
    Availability: Unix, Windows.
 
 
+.. data:: supports_bytes_environ
+
+   True if the native OS type of the environment is bytes (eg. False on
+   Windows). :data:`environb` is only available if
+   :data:`supports_bytes_environ` is True.
+
 .. function:: umask(mask)
 
    Set the current numeric umask and return the previous umask.
Index: Lib/os.py
===================================================================
--- Lib/os.py	(révision 81236)
+++ Lib/os.py	(copie de travail)
@@ -355,7 +355,11 @@
         return
     last_exc = saved_exc = None
     saved_tb = None
-    for dir in get_exec_path(env):
+    path_list = get_exec_path(env)
+    if name != 'nt':
+        file = fsencode(file)
+        path_list = map(fsencode, path_list)
+    for dir in path_list:
         fullname = path.join(dir, file)
         try:
             exec_func(fullname, *argrest)
@@ -380,7 +384,24 @@
     """
     if env is None:
         env = environ
-    return env.get('PATH', defpath).split(pathsep)
+    try:
+        path_list = env.get('PATH')
+    except TypeError:
+        path_list = None
+    if supports_bytes_environ:
+        try:
+            path_listb = env[b'PATH']
+        except (KeyError, TypeError):
+            pass
+        else:
+            if path_list is not None:
+                raise ValueError(
+                    "env contains two PATH variables of different types")
+            path_list = path_listb.decode(sys.getfilesystemencoding(),
+                                          'surrogateescape')
+    if path_list is None:
+        path_list = defpath
+    return path_list.split(pathsep)
 
 
 # Change environ to automatically call putenv(), unsetenv if they exist.
@@ -482,9 +503,11 @@
     The optional second argument can specify an alternate default.
     key, default and the result are str."""
     return environ.get(key, default)
-__all__.append("getenv")
 
-if name not in ('os2', 'nt'):
+supports_bytes_environ = name not in ('os2', 'nt')
+__all__.extend(("getenv", "supports_bytes_environ"))
+
+if supports_bytes_environ:
     def _check_bytes(value):
         if not isinstance(value, bytes):
             raise TypeError("bytes expected, not %s" % type(value).__name__)
Index: Lib/test/test_subprocess.py
===================================================================
--- Lib/test/test_subprocess.py	(révision 81236)
+++ Lib/test/test_subprocess.py	(copie de travail)
@@ -825,7 +825,23 @@
             stdout = stdout.rstrip(b'\n\r')
             self.assertEquals(stdout.decode('ascii'), repr(value))
 
+    def test_bytes_program(self):
+        path, program = os.path.split(sys.executable)
+        program = os.fsencode(program)
 
+        # bytes program, unicode PATH
+        env = os.environ.copy()
+        env["PATH"] = path
+        exitcode = subprocess.call([program, "-c", "pass"], env=env)
+        self.assertEquals(exitcode, 0)
+
+        # bytes program, bytes PATH
+        envb = os.environb.copy()
+        envb[b"PATH"] = os.fsencode(path)
+        exitcode = subprocess.call([program, "-c", "pass"], env=envb)
+        self.assertEquals(exitcode, 0)
+
+
 @unittest.skipUnless(mswindows, "Windows specific tests")
 class Win32ProcessTestCase(BaseTestCase):
 
Index: Lib/subprocess.py
===================================================================
--- Lib/subprocess.py	(révision 81236)
+++ Lib/subprocess.py	(copie de travail)
@@ -1096,15 +1096,14 @@
                                         for k, v in env.items()]
                         else:
                             env_list = None  # Use execv instead of execve.
+                        executable = os.fsencode(executable)
                         if os.path.dirname(executable):
-                            executable_list = (os.fsencode(executable),)
+                            executable_list = (executable,)
                         else:
                             # This matches the behavior of os._execvpe().
-                            path_list = os.get_exec_path(env)
-                            executable_list = (os.path.join(dir, executable)
-                                               for dir in path_list)
-                            executable_list = tuple(os.fsencode(exe)
-                                                    for exe in executable_list)
+                            executable_list = tuple(
+                                os.path.join(os.fsencode(dir), executable)
+                                for dir in os.get_exec_path(env))
                         self.pid = _posixsubprocess.fork_exec(
                                 args, executable_list,
                                 close_fds, cwd, env_list,