--- a/testing/web-platform/update/upstream.py
+++ b/testing/web-platform/update/upstream.py
@@ -87,21 +87,21 @@ class CheckoutBranch(Step):
     """Create a branch in the sync tree pointing at the last upstream sync commit
     and check it out"""
 
     provides = ["branch"]
 
     def create(self, state):
         self.logger.info("Updating sync tree from %s" % state.sync["remote_url"])
         state.branch = state.sync_tree.unique_branch_name(
-            "outbound_update_%s" % state.test_manifest.rev)
+            "outbound_update_%s" % state.old_manifest.rev)
         state.sync_tree.update(state.sync["remote_url"],
                                state.sync["branch"],
                                state.branch)
-        state.sync_tree.checkout(state.test_manifest.rev, state.branch, force=True)
+        state.sync_tree.checkout(state.old_manifest.rev, state.branch, force=True)
 
 
 class GetLastSyncCommit(Step):
     """Find the gecko commit at which we last performed a sync with upstream."""
 
     provides = ["last_sync_path", "last_sync_commit"]
 
     def create(self, state):