diff --git a/mercurial/hook.py b/mercurial/hook.py
--- a/mercurial/hook.py
+++ b/mercurial/hook.py
@@ -106,6 +106,8 @@ def _pythonhook(ui, repo, name, hname, f
                            '%s\n') % (hname, exc))
         if throw:
             raise
+        if not ui.tracebackflag:
+            ui.warn(_('(run with --traceback for stack trace)\n'))
         ui.traceback()
         return True, True
     finally:
diff --git a/tests/test-hook.t b/tests/test-hook.t
--- a/tests/test-hook.t
+++ b/tests/test-hook.t
@@ -541,6 +541,7 @@ post- python hooks that fail to *run* do
   searching for changes
   no changes found
   error: post-pull.broken hook raised an exception: unsupported operand type(s) for +: 'int' and 'dict'
+  (run with --traceback for stack trace)
 
 but post- python hooks that fail to *load* do
   $ echo '[hooks]' > .hg/hgrc