Products.ERP5Security._setUserNameForAccessLog: Do nothing on Zope4

The way Zope4 logs the authenticated user is radically different from
Zope2, and makes this function useless.
So, unless when running on Zope2, do nothing when this function is called.

product/ERP5Security/__init__.py

@@ -24,6 +24,7 @@ from Acquisition import aq_inner, aq_parent
 from AccessControl.Permissions import manage_users as ManageUsers
 from Products.PluggableAuthService.PluggableAuthService import registerMultiPlugin
 from Products.PluggableAuthService.permissions import ManageGroups
+from Products.ERP5Type import IS_ZOPE2
 import six
 
 # This user is used to bypass all security checks.
@@ -57,7 +58,8 @@ def mergedLocalRoles(object):
   return deepcopy(merged)
 
 
-def _setUserNameForAccessLog(username, REQUEST):
+if IS_ZOPE2: # BBB
+  def _setUserNameForAccessLog(username, REQUEST):
     """Make the current user look as `username` in Zope's Z2.log
 
     Taken from Products.CMFCore.CookieCrumbler._setAuthHeader
@@ -78,6 +80,12 @@ def _setUserNameForAccessLog(username, REQUEST):
         medusa_headers['authorization'] = 'Basic %s' % encodestring('%s:' % username).rstrip()
     else:
       REQUEST._orig_env['REMOTE_USER'] = username
+else: # zope4
+  def _setUserNameForAccessLog(username, REQUEST):
+    """
+    Nothing to do for this on Zope4.
+    """
+    pass
 
 
 def initialize(context):