Backout a1a05e2724dd: shutil.which(bytes) is a new feature and my patch does not work on Windows

Doc/library/shutil.rst

@@ -352,10 +352,6 @@ Directory and files operations
 
    .. versionadded:: 3.3
 
-   .. versionchanged:: 3.4
-      The :class:`bytes` type is now accepted. If *cmd* type is :class:`bytes`,
-      the result type is also :class:`bytes`.
-
 
 .. exception:: Error
 

Lib/shutil.py

@@ -1065,13 +1065,6 @@ def get_terminal_size(fallback=(80, 24)):
 
     return os.terminal_size((columns, lines))
 
-# Check that a given file can be accessed with the correct mode.
-# Additionally check that `file` is not a directory, as on Windows
-# directories pass the os.access check.
-def _access_check(fn, mode):
-    return (os.path.exists(fn) and os.access(fn, mode)
-            and not os.path.isdir(fn))
-
 def which(cmd, mode=os.F_OK | os.X_OK, path=None):
     """Given a command, mode, and a PATH string, return the path which
     conforms to the given mode on the PATH, or None if there is no such
@@ -1082,6 +1075,13 @@ def which(cmd, mode=os.F_OK | os.X_OK, path=None):
     path.
 
     """
+    # Check that a given file can be accessed with the correct mode.
+    # Additionally check that `file` is not a directory, as on Windows
+    # directories pass the os.access check.
+    def _access_check(fn, mode):
+        return (os.path.exists(fn) and os.access(fn, mode)
+                and not os.path.isdir(fn))
+
     # If we're given a path with a directory part, look it up directly rather
     # than referring to PATH directories. This includes checking relative to the
     # current directory, e.g. ./script
@@ -1094,11 +1094,6 @@ def which(cmd, mode=os.F_OK | os.X_OK, path=None):
         path = os.environ.get("PATH", os.defpath)
     if not path:
         return None
-    if isinstance(cmd, bytes):
-        path = os.fsencode(path)
-        path = path.split(os.fsencode(os.pathsep))
-    else:
-        path = os.fsdecode(path)
     path = path.split(os.pathsep)
 
     if sys.platform == "win32":
@@ -1108,8 +1103,6 @@ def which(cmd, mode=os.F_OK | os.X_OK, path=None):
 
         # PATHEXT is necessary to check on Windows.
         pathext = os.environ.get("PATHEXT", "").split(os.pathsep)
-        if isinstance(cmd, bytes):
-            pathext = map(os.fsencode, pathext)
         # See if the given file matches any of the expected path extensions.
         # This will allow us to short circuit when given "python.exe".
         # If it does match, only test that one, otherwise we have to try

Lib/test/test_shutil.py

@@ -1326,7 +1326,6 @@ class TestWhich(unittest.TestCase):
         os.chmod(self.temp_file.name, stat.S_IXUSR)
         self.addCleanup(self.temp_file.close)
         self.dir, self.file = os.path.split(self.temp_file.name)
-        self.env_path = self.dir
 
     def test_basic(self):
         # Given an EXE in a directory, it should be returned.
@@ -1395,7 +1394,7 @@ class TestWhich(unittest.TestCase):
 
     def test_environ_path(self):
         with support.EnvironmentVarGuard() as env:
-            env['PATH'] = self.env_path
+            env['PATH'] = self.dir
             rv = shutil.which(self.file)
             self.assertEqual(rv, self.temp_file.name)
 
@@ -1403,7 +1402,7 @@ class TestWhich(unittest.TestCase):
         base_dir = os.path.dirname(self.dir)
         with support.change_cwd(path=self.dir), \
              support.EnvironmentVarGuard() as env:
-            env['PATH'] = self.env_path
+            env['PATH'] = self.dir
             rv = shutil.which(self.file, path='')
             self.assertIsNone(rv)
 
@@ -1414,14 +1413,6 @@ class TestWhich(unittest.TestCase):
             self.assertIsNone(rv)
 
 
-class TestWhichBytes(TestWhich):
-    def setUp(self):
-        TestWhich.setUp(self)
-        self.dir = os.fsencode(self.dir)
-        self.file = os.fsencode(self.file)
-        self.temp_file.name = os.fsencode(self.temp_file.name)
-
-
 class TestMove(unittest.TestCase):
 
     def setUp(self):

Misc/NEWS

@@ -44,8 +44,6 @@ Core and Builtins
 Library
 -------
 
-- Issue #18283: shutil.which() now supports bytes argument, not only text argument.
-
 - Issue #19921: When Path.mkdir() is called with parents=True, any missing
   parent is created with the default permissions, ignoring the mode argument
   (mimicking the POSIX "mkdir -p" command).