bpo-44368: Ensure we don't raise incorrect custom syntax errors with soft keywords (GH-26630)

(cherry picked from commit 457ce60fc70f1c9290023f46fb82b6a490dff32e)

Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
diff --git a/Lib/test/test_exceptions.py b/Lib/test/test_exceptions.py
index b242c08..9cb5466 100644
--- a/Lib/test/test_exceptions.py
+++ b/Lib/test/test_exceptions.py
@@ -215,6 +215,7 @@ def testSyntaxErrorOffset(self):
         check('[\nfile\nfor str(file)\nin\n[]\n]', 3, 5)
         check('[file for\n str(file) in []]', 2, 2)
         check("ages = {'Alice'=22, 'Bob'=23}", 1, 16)
+        check('match ...:\n    case {**rest, "key": value}:\n        ...', 2, 19)
 
         # Errors thrown by compile.c
         check('class foo:return 1', 1, 11)