--- a/tests/run-tests.py	Thu Apr 13 09:49:48 2017 +0200
+++ b/tests/run-tests.py	Tue Apr 04 11:03:29 2017 +0200
@@ -884,6 +884,7 @@
         env = os.environ.copy()
         if sysconfig is not None:
             env['PYTHONUSERBASE'] = sysconfig.get_config_var('userbase')
+        env['HGEMITWARNINGS'] = '1'
         env['TESTTMP'] = self._testtmp
         env['HOME'] = self._testtmp
         # This number should match portneeded in _getport