--- a/mercurial/chgserver.py	Tue Dec 13 20:53:40 2016 +0530
+++ b/mercurial/chgserver.py	Wed Dec 14 02:17:59 2016 +0000
@@ -77,7 +77,7 @@
 # sensitive environment variables affecting confighash
 _envre = re.compile(r'''\A(?:
                     CHGHG
-                    |HG.*
+                    |HG(?:[A-Z].*)?
                     |LANG(?:UAGE)?
                     |LC_.*
                     |LD_.*