diff --git a/tests/test-unbundlehash.t b/tests/test-unbundlehash.t
--- a/tests/test-unbundlehash.t
+++ b/tests/test-unbundlehash.t
@@ -2,6 +2,14 @@
 
 Test wire protocol unbundle with hashed heads (capability: unbundlehash)
 
+  $ cat << EOF >> $HGRCPATH
+  > [experimental]
+  > # This tests is intended for bundle1 only.
+  > # bundle2 carries the head information inside the bundle itself and
+  > # always uses 'force' as the heads value.
+  > bundle2-exp = False
+  > EOF
+
 Create a remote repository.
 
   $ hg init remote