diff -r 33b7283a3828 -r 23734c0e361f mercurial/debugcommands.py
--- a/mercurial/debugcommands.py	Fri Jun 09 10:41:13 2017 -0700
+++ b/mercurial/debugcommands.py	Fri Jun 09 10:42:19 2017 -0700
@@ -47,6 +47,7 @@
     lock as lockmod,
     merge as mergemod,
     obsolete,
+    phases,
     policy,
     pvec,
     pycompat,
@@ -421,6 +422,12 @@
     Stream bundles are special bundles that are essentially archives of
     revlog files. They are commonly used for cloning very quickly.
     """
+    # TODO we may want to turn this into an abort when this functionality
+    # is moved into `hg bundle`.
+    if phases.hassecret(repo):
+        ui.warn(_('(warning: stream clone bundle will contain secret '
+                  'revisions)\n'))
+
     requirements, gen = streamclone.generatebundlev1(repo)
     changegroup.writechunks(ui, gen, fname)