xhtml_style: fix rendering of standard_error_message when site title is not ASCII

When rendering error page, the default header_title is computed in global_definitions
and this is done by concatenating string:ERP5 (which is unicode) and the
title of the portal (which is an UTF-8 encoded string), which causes an
UnicodeDecodeError, because the portal title was decoded as ASCII.

Because header_title is usually an UTF-8 encoded string, also use an UTF-8
encoded string for 'ERP5' default value.

bt5/erp5_core_test/TestTemplateItem/portal_components/test.erp5.testERP5Core.py

 ##############################################################################
-#
+# coding: utf-8
 # Copyright (c) 2004, 2005, 2006 Nexedi SARL and Contributors.
 # All Rights Reserved.
 #          Romain Courteaud <romain@nexedi.com>
@@ -32,6 +32,7 @@ import httplib
 import urlparse
 import base64
 import urllib
+import lxml.html
 
 from AccessControl.SecurityManagement import newSecurityManager
 from Testing import ZopeTestCase
@@ -647,6 +648,31 @@ class TestERP5Core(ERP5TypeTestCase, ZopeTestCase.Functional):
     self.assertEqual(response.status, 401)
     self.assertEqual(response.getheader('WWW-Authenticate'), None)
 
+  def test_non_ascii_site_title(self):
+    self.portal.setTitle('文字化け')
+    self.assertEqual(
+        lxml.html.fromstring(self.portal.view()).find('.//div[@id="breadcrumb"]/a').text,
+        u'文字化け')
+    self.assertEqual(
+        lxml.html.fromstring(
+            self.portal.person_module.view()
+        ).find('.//div[@id="breadcrumb"]/a').text,
+        u'文字化け')
+    self.assertEqual(
+        lxml.html.fromstring(
+            self.portal.person_module.newContent(portal_type='Person').view()
+        ).find('.//div[@id="breadcrumb"]/a').text,
+        u'文字化け')
+
+  def test_standard_error_message_non_ascii(self):
+    # regression test for error message when portal title is not ASCII
+    self.portal.setTitle('文字化け')
+    self.assertIn(
+        u'文字化け',
+        self.portal.standard_error_message(
+            error_type="MyErrorType",
+            error_message="my error message."))
+
   def test_standardErrorMessageShouldNotRaiseUnauthorizeOnUnauthorizeDocument(self):
     """
       When trying to show the `standard_error_message` on a document that user

product/ERP5/bootstrap/erp5_xhtml_style/SkinTemplateItem/portal_skins/erp5_xhtml_style/global_definitions.zpt

@@ -46,7 +46,7 @@
     <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
     <title
       tal:define="
-        title title | string:ERP5;
+        title title | python:'ERP5';
         header_title header_title | nothing;
       "
       tal:content="python: header_title or '%s | %s' % (title, here.getPortalObject().title_or_id())"