Drop all cache of a database when it is dropped

issue4584
review11121002

trytond/cache.py

@@ -116,6 +116,11 @@ class Cache(object):
                 Cache._resets[dbname].clear()
             cursor.commit()
 
+    @classmethod
+    def drop(cls, dbname):
+        for inst in cls._cache_instance:
+            inst._cache.pop(dbname, None)
+
 
 class LRUDict(OrderedDict):
     """

trytond/protocols/dispatcher.py

@@ -269,6 +269,7 @@ def drop(database_name, password):
         else:
             logger.info('DROP DB: %s', database_name)
             Pool.stop(database_name)
+            Cache.drop(database_name)
     return True