mercurial/cmdutil.py

--- a/mercurial/cmdutil.py	Fri Nov 15 15:58:56 2019 -0500
+++ b/mercurial/cmdutil.py	Thu Nov 21 09:25:50 2019 +0100
@@ -1771,6 +1771,8 @@
             overrides = {}
             if partial:
                 overrides[(b'ui', b'allowemptycommit')] = True
+            if opts.get(b'secret'):
+                overrides[(b'phases', b'new-commit')] = b'secret'
             with repo.ui.configoverride(overrides, b'import'):
                 n = repo.commit(
                     message, user, date, match=m, editor=editor, extra=extra