diff --git a/contrib/python3-whitelist b/contrib/python3-whitelist
--- a/contrib/python3-whitelist
+++ b/contrib/python3-whitelist
@@ -70,6 +70,7 @@
 test-clone-uncompressed.t
 test-clone-update-order.t
 test-clonebundles.t
+test-close-head.t
 test-commit-amend.t
 test-commit-interactive.t
 test-commit-multiple.t
diff --git a/hgext/closehead.py b/hgext/closehead.py
--- a/hgext/closehead.py
+++ b/hgext/closehead.py
@@ -66,7 +66,7 @@
     heads = set(repo[h].rev() for h in heads)
     for rev in revs:
         if rev not in heads:
-            raise error.Abort(_('revision is not an open head: %s') % rev)
+            raise error.Abort(_('revision is not an open head: %d') % rev)
 
     message = cmdutil.logmessage(ui, opts)
     if not message: