--- a/tests/run-tests.py	Fri Jan 06 14:35:22 2017 +0100
+++ b/tests/run-tests.py	Fri Jan 06 16:19:41 2017 +0000
@@ -849,7 +849,7 @@
         env['TERM'] = 'xterm'
 
         for k in ('HG HGPROF CDPATH GREP_OPTIONS http_proxy no_proxy ' +
-                  'NO_PROXY').split():
+                  'NO_PROXY CHGDEBUG').split():
             if k in env:
                 del env[k]