diff -r 6994a8be3663 -r ddeb510d6815 mercurial/testing/storage.py
--- a/mercurial/testing/storage.py	Tue Oct 16 17:45:39 2018 +0200
+++ b/mercurial/testing/storage.py	Tue Oct 16 15:24:06 2018 +0200
@@ -1073,14 +1073,7 @@
         fulltext0 = b'foo'
         delta0 = mdiff.trivialdiffheader(len(fulltext0)) + fulltext0
 
-        deltas = [
-            (b'\x01' * 20, nullid, nullid, nullid, nullid, delta0, 0),
-        ]
-
         with self._maketransactionfn() as tr:
-            with self.assertRaises(error.StorageError):
-                f.addgroup(deltas, linkmapper, tr, addrevisioncb=cb)
-
             node0 = f.add(fulltext0, None, tr, 0, nullid, nullid)
 
         f = self._makefilefn()