ERP5Type: Don't log when cache factory is not found

This should prevent all the warnings like

    WARNING Cache.__call__ Factory erp5_content_medium not found, method <function getTypeList at 0x7fd8b2ce4cd0> executed without cache
    WARNING Cache.__call__ Factory erp5_content_long not found, method <function _getPortalGroupedTypeSet at 0x7fd8bc613750> executed without cache

we have during startup.

This code tried to detect the case where cache system was not
fully initialized an only log in this case, but there does not seem to
be a reliable way to detect that cache is supposed to be ready and that
log was not really useful - If some methods are executed without cache
for some reason (which as far as I know never happens), then we should
be able to notice the problem because it's slow.

product/ERP5Type/Cache.py

@@ -43,29 +43,25 @@ from warnings import warn
 
 DEFAULT_CACHE_SCOPE = 'GLOBAL'
 DEFAULT_CACHE_FACTORY = 'erp5_ui_short'
-is_cache_initialized = 0
-is_cache_ready = 0
+is_cache_initialized = False
+
 
 def initializePortalCachingProperties(self):
   """ Init CachingMethod properties."""
   ## check if global CachingMethod is initialized in RAM for this ERP5 site. If not init it
   global is_cache_initialized
-  global is_cache_ready
   if not is_cache_initialized:
     portal_caches = getattr(self.getPortalObject(), 'portal_caches', None)
     if portal_caches is None:
       return
     # we set is_cache_initialized right now to prevent infinite loops
-    is_cache_initialized = 1
+    is_cache_initialized = True
     ## update cache structure from portal_caches
     try:
       portal_caches.updateCache()
     except AttributeError:
-      is_cache_initialized = 0
+      is_cache_initialized = False
       return
-    # we mark the cache as ready after initialization, because initialization
-    # itself will cause cache misses that we want to ignore
-    is_cache_ready = 1
 
 
 class ZODBCookie(Persistent):
@@ -272,12 +268,8 @@ class CachingMethod:
       # on CachingMethod instead of self, we want a global variable
       cache_factory = CachingMethod.factories[self.cache_factory]
     except KeyError:
-      global is_cache_ready
-      if is_cache_ready:
-        ## no caching enabled for this site or no such cache factory
-        LOG("Cache.__call__", WARNING,
-            "Factory %s not found, method %s executed without cache" % (
-             self.cache_factory, self.callable_object))
+      # No cache factory ready, execute without cache. This happens during
+      # initialisation
       value = self.callable_object(*args, **kwd)
     else:
       value = cache_factory(