--- a/tests/test-rust-ancestor.py	Thu Aug 10 11:01:07 2023 +0200
+++ b/tests/test-rust-ancestor.py	Fri Aug 18 14:34:29 2023 +0200
@@ -2,7 +2,6 @@
 import unittest
 
 from mercurial.node import wdirrev
-from mercurial import error
 
 from mercurial.testing import revlog as revlogtesting
 
@@ -144,11 +143,15 @@
 
     def testwdirunsupported(self):
         # trying to access ancestors of the working directory raises
-        # WdirUnsupported directly
         idx = self.parseindex()
-        with self.assertRaises(error.WdirUnsupported):
+        with self.assertRaises(rustext.GraphError) as arc:
             list(AncestorsIterator(idx, [wdirrev], -1, False))
 
+        exc = arc.exception
+        self.assertIsInstance(exc, ValueError)
+        # rust-cpython issues appropriate str instances for Python 2 and 3
+        self.assertEqual(exc.args, ('InvalidRevision', wdirrev))
+
     def testheadrevs(self):
         idx = self.parseindex()
         self.assertEqual(dagop.headrevs(idx, [1, 2, 3]), {3})