diff -r da5fa0f13a41 -r bd5e9647f646 mercurial/cmdutil.py
--- a/mercurial/cmdutil.py	Tue Jan 17 23:05:12 2017 -0500
+++ b/mercurial/cmdutil.py	Tue Jan 17 23:12:54 2017 -0500
@@ -1448,6 +1448,7 @@
             'parent': '{rev}:{node|formatnode} ',
             'manifest': '{rev}:{node|formatnode}',
             'file_copy': '{name} ({source})',
+            'envvar': '{key}={value}',
             'extra': '{key}={value|stringescape}'
             }
         # filecopy is preserved for compatibility reasons