Test: drop use of 'tag' decorator

test/unittest_views.py

 import unittest
-from logilab.common.testlib import tag
 
 from cubicweb.devtools.testlib import CubicWebTC
 from cubicweb.devtools.htmlparser import XMLValidator
@@ -7,12 +6,10 @@ from cubicweb.devtools.htmlparser import XMLValidator
 
 class BoostrapTheMainTemplateTC(CubicWebTC):
 
-    @tag('index')
     def test_valid_xhtml_index(self):
         with self.admin_access.web_request() as req:
             self.view('index', req=req)
 
-    @tag('error')
     def test_valid_xhtml_error(self):
         valid = self.content_type_validators.get('text/html', XMLValidator)()
         with self.admin_access.web_request() as req: