--- a/hgext/configwizard/__init__.py
+++ b/hgext/configwizard/__init__.py
@@ -11,16 +11,17 @@ import subprocess
 import sys
 import uuid
 
 from mercurial import (
     cmdutil,
     demandimport,
     error,
     scmutil,
+    ui as uimod,
     util,
 )
 from mercurial.i18n import _
 
 OUR_DIR = os.path.dirname(__file__)
 execfile(os.path.join(OUR_DIR, '..', 'bootstrap.py'))
 
 from configobj import ConfigObj
@@ -815,8 +816,20 @@ class configobjwrapper(object):
     def write(self, fh):
         lines = self.c.write()
         for line in lines:
             if line.startswith('#%s ' % self._random):
                 line = line[2 + len(self._random):]
 
             fh.write('%s\n' % line)
 
+
+def uisetup(ui):
+    # hasconfig() was added in 3.7. Backport until we require 3.7.
+    if util.safehasattr(ui, 'hasconfig'):
+        return
+
+    class configui(ui.__class__):
+        def hasconfig(self, section, name, untrusted=False):
+            return name in self._data(untrusted)._data.get(section, {})
+
+    ui.__class__ = configui
+    uimod.ui = configui