Issue #19856: shutil.move() failed to move a directory to other directory

on Windows if source name ends with os.altsep.

Lib/shutil.py

@@ -484,7 +484,8 @@ rmtree.avoids_symlink_attacks = _use_fd_functions
 def _basename(path):
     # A basename() variant which first strips the trailing slash, if present.
     # Thus we always get the last component of the path, even for directories.
-    return os.path.basename(path.rstrip(os.path.sep))
+    sep = os.path.sep + (os.path.altsep or '')
+    return os.path.basename(path.rstrip(sep))
 
 def move(src, dst):
     """Recursively move a file or directory to another location. This is

Lib/test/test_shutil.py

@@ -1481,6 +1481,15 @@ class TestMove(unittest.TestCase):
         # Move a dir inside an existing dir on another filesystem.
         self.test_move_dir_to_dir()
 
+    def test_move_dir_sep_to_dir(self):
+        self._check_move_dir(self.src_dir + os.path.sep, self.dst_dir,
+            os.path.join(self.dst_dir, os.path.basename(self.src_dir)))
+
+    @unittest.skipUnless(os.path.altsep, 'requires os.path.altsep')
+    def test_move_dir_altsep_to_dir(self):
+        self._check_move_dir(self.src_dir + os.path.altsep, self.dst_dir,
+            os.path.join(self.dst_dir, os.path.basename(self.src_dir)))
+
     def test_existing_file_inside_dest_dir(self):
         # A file with the same name inside the destination dir already exists.
         with open(self.dst_file, "wb"):

Misc/NEWS

@@ -20,6 +20,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #19856: shutil.move() failed to move a directory to other directory
+  on Windows if source name ends with os.altsep.
+
 - Issue #14983: email.generator now always adds a line end after each MIME
   boundary marker, instead of doing so only when there is an epilogue.  This
   fixes an RFC compliance bug and solves an issue with signed MIME parts.