[FIX] fields: copy origin to avoid sharing field objects between registries

Fix a bug introduced in revision f229974, where shared columns objects are
systematically reintroduced in registries.

openerp/fields.py

@@ -598,7 +598,9 @@ class Field(object):
         assert self.store
         if self._origin:
             assert isinstance(self._origin, fields._column)
-            return self._origin
+            # some columns are registry-dependent, like float fields (digits);
+            # duplicate them to avoid sharing between registries
+            return copy(self._origin)
 
         _logger.debug("Create fields._column for Field %s", self)
         args = {}

openerp/models.py

@@ -39,7 +39,6 @@
 
 """
 
-import copy
 import datetime
 import functools
 import itertools
@@ -653,12 +652,6 @@ class BaseModel(object):
         }
         cls = type(cls._name, (cls,), attrs)
 
-        # float fields are registry-dependent (digit attribute); duplicate them
-        # to avoid issues
-        for key, col in cls._columns.items():
-            if col._type == 'float':
-                cls._columns[key] = copy.copy(col)
-
         # instantiate the model, and initialize it
         model = object.__new__(cls)
         model.__init__(pool, cr)