Issue #23742: ntpath.expandvars() no longer loses unbalanced single quotes.

Lib/ntpath.py

@@ -400,7 +400,7 @@ def expandvars(path):
                 index = path.index(c)
                 res += c + path[:index + 1]
             except ValueError:
-                res += path
+                res += c + path
                 index = pathlen - 1
         elif c == percent:  # variable or '%'
             if path[index + 1:index + 2] == percent:

Lib/test/test_ntpath.py

@@ -237,6 +237,7 @@ class TestNtpath(unittest.TestCase):
             tester('ntpath.expandvars("%?bar%")', "%?bar%")
             tester('ntpath.expandvars("%foo%%bar")', "bar%bar")
             tester('ntpath.expandvars("\'%foo%\'%bar")', "\'%foo%\'%bar")
+            tester('ntpath.expandvars("bar\'%foo%")', "bar\'%foo%")
 
     @unittest.skipUnless(support.FS_NONASCII, 'need support.FS_NONASCII')
     def test_expandvars_nonascii(self):

Misc/NEWS

@@ -18,6 +18,8 @@ Core and Builtins
 Library
 -------
 
+- Issue #23742: ntpath.expandvars() no longer loses unbalanced single quotes.
+
 - Issue #21802: The reader in BufferedRWPair now is closed even when closing
   writer failed in BufferedRWPair.close().