MemcacheDict does not implement delete

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@29107 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Type/CachePlugins/DistributedRamCache.py

@@ -109,7 +109,7 @@ class DistributedRamCache(BaseCache):
     # since some memcached-like products does not support expiration, we
     # check it by ourselves.
     if cache_entry.isExpired():
-      cache_storage.delete(cache_id)
+      del cache_storage[cache_id]
       return default
     self.markCacheHit()
     return cache_entry