Fill ModelStorage caches only for records no further away then the read size

The read size is the size limit of the cache so filling it for record further
away will discard existing value closest.

trytond/trytond/model/modelstorage.py

@@ -1773,9 +1773,8 @@ class ModelStorage(Model):
                 self._cache.size_limit, self._local_cache.size_limit,
                 self._transaction.database.IN_MAX))
         index = self._ids.index(self.id)
-        ids = chain(islice(self._ids, index, None),
-            islice(self._ids, 0, max(index - 1, 0)))
-        ids = islice(unique(filter(filter_, ids)), read_size)
+        ids = islice(self._ids, index, index + read_size)
+        ids = unique(filter(filter_, ids))
 
         kwargs_cache = {}
         pysoned_ctx = {}
@@ -1849,9 +1848,7 @@ class ModelStorage(Model):
                     and ffields.keys() <= set(self._cache[self.id]._keys())):
                 # Use values from cache
                 read_data = []
-                for id_ in islice(chain(islice(self._ids, index, None),
-                            islice(self._ids, 0, max(index - 1, 0))),
-                        read_size):
+                for id_ in islice(self._ids, index, index + read_size):
                     if id_ in self._cache:
                         data = {'id': id_}
                         for fname in ffields: