We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
Copying items not work correctly with list values
> > item = Item()
> > item['some_field'] = []
> > 
> > c_item = Item(item)
> > c_item['some_field'].append(1)
> > 
> > print item['some_field'], c_item['some_field']
> > [1] [1]


--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `scrapy/item.py`
Content:
```
1 """
2 Scrapy Item
3 
4 See documentation in docs/topics/item.rst
5 """
6 
7 from pprint import pformat
8 from collections import MutableMapping
9 
10 from abc import ABCMeta
11 import six
12 
13 from scrapy.utils.trackref import object_ref
14 
15 
16 class BaseItem(object_ref):
17     """Base class for all scraped items."""
18     pass
19 
20 
21 class Field(dict):
22     """Container of field metadata"""
23 
24 
25 class ItemMeta(ABCMeta):
26 
27     def __new__(mcs, class_name, bases, attrs):
28         classcell = attrs.pop('__classcell__', None)
29         new_bases = tuple(base._class for base in bases if hasattr(base, '_class'))
30         _class = super(ItemMeta, mcs).__new__(mcs, 'x_' + class_name, new_bases, attrs)
31 
32         fields = getattr(_class, 'fields', {})
33         new_attrs = {}
34         for n in dir(_class):
35             v = getattr(_class, n)
36             if isinstance(v, Field):
37                 fields[n] = v
38             elif n in attrs:
39                 new_attrs[n] = attrs[n]
40 
41         new_attrs['fields'] = fields
42         new_attrs['_class'] = _class
43         if classcell is not None:
44             new_attrs['__classcell__'] = classcell
45         return super(ItemMeta, mcs).__new__(mcs, class_name, bases, new_attrs)
46 
47 
48 class DictItem(MutableMapping, BaseItem):
49 
50     fields = {}
51 
52     def __init__(self, *args, **kwargs):
53         self._values = {}
54         if args or kwargs:  # avoid creating dict for most common case
55             for k, v in six.iteritems(dict(*args, **kwargs)):
56                 self[k] = v
57 
58     def __getitem__(self, key):
59         return self._values[key]
60 
61     def __setitem__(self, key, value):
62         if key in self.fields:
63             self._values[key] = value
64         else:
65             raise KeyError("%s does not support field: %s" %
66                 (self.__class__.__name__, key))
67 
68     def __delitem__(self, key):
69         del self._values[key]
70 
71     def __getattr__(self, name):
72         if name in self.fields:
73             raise AttributeError("Use item[%r] to get field value" % name)
74         raise AttributeError(name)
75 
76     def __setattr__(self, name, value):
77         if not name.startswith('_'):
78             raise AttributeError("Use item[%r] = %r to set field value" %
79                 (name, value))
80         super(DictItem, self).__setattr__(name, value)
81 
82     def __len__(self):
83         return len(self._values)
84 
85     def __iter__(self):
86         return iter(self._values)
87 
88     __hash__ = BaseItem.__hash__
89 
90     def keys(self):
91         return self._values.keys()
92 
93     def __repr__(self):
94         return pformat(dict(self))
95 
96     def copy(self):
97         return self.__class__(self)
98 
99 
100 @six.add_metaclass(ItemMeta)
101 class Item(DictItem):
102     pass
103
```
--- END FILES ---

Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.

Here is an example:

```diff
diff --git a/examples/server_async.py b/examples/server_async.py
--- a/examples/server_async.py
+++ b/examples/server_async.py
@@ -313,4 +313,4 @@
 
 
 if __name__ == "__main__":
-    asyncio.run(run_async_server("."), debug=True)
+    asyncio.run(run_async_server(), debug=True)
diff --git a/examples/server_sync.py b/examples/server_sync.py
--- a/examples/server_sync.py
+++ b/examples/server_sync.py
@@ -313,5 +313,5 @@
 
 
 if __name__ == "__main__":
-    server = run_sync_server(".")
+    server = run_sync_server()
     server.shutdown()

```

diff --git a/scrapy/item.py b/scrapy/item.py
--- a/scrapy/item.py
+++ b/scrapy/item.py
@@ -6,6 +6,7 @@
 
 from pprint import pformat
 from collections import MutableMapping
+from copy import deepcopy
 
 from abc import ABCMeta
 import six
@@ -96,6 +97,13 @@
     def copy(self):
         return self.__class__(self)
 
+    def deepcopy(self):
+        """Return a `deep copy`_ of this item.
+
+        .. _deep copy: https://docs.python.org/library/copy.html#copy.deepcopy
+        """
+        return deepcopy(self)
+
 
 @six.add_metaclass(ItemMeta)
 class Item(DictItem):

{"golden_diff": "diff --git a/scrapy/item.py b/scrapy/item.py\n--- a/scrapy/item.py\n+++ b/scrapy/item.py\n@@ -6,6 +6,7 @@\n \n from pprint import pformat\n from collections import MutableMapping\n+from copy import deepcopy\n \n from abc import ABCMeta\n import six\n@@ -96,6 +97,13 @@\n     def copy(self):\n         return self.__class__(self)\n \n+    def deepcopy(self):\n+        \"\"\"Return a `deep copy`_ of this item.\n+\n+        .. _deep copy: https://docs.python.org/library/copy.html#copy.deepcopy\n+        \"\"\"\n+        return deepcopy(self)\n+\n \n @six.add_metaclass(ItemMeta)\n class Item(DictItem):\n", "issue": "Copying items not work correctly with list values\n> > item = Item()\n> > item['some_field'] = []\n> > \n> > c_item = Item(item)\n> > c_item['some_field'].append(1)\n> > \n> > print item['some_field'], c_item['some_field']\n> > [1] [1]\n\n", "before_files": [{"content": "\"\"\"\nScrapy Item\n\nSee documentation in docs/topics/item.rst\n\"\"\"\n\nfrom pprint import pformat\nfrom collections import MutableMapping\n\nfrom abc import ABCMeta\nimport six\n\nfrom scrapy.utils.trackref import object_ref\n\n\nclass BaseItem(object_ref):\n    \"\"\"Base class for all scraped items.\"\"\"\n    pass\n\n\nclass Field(dict):\n    \"\"\"Container of field metadata\"\"\"\n\n\nclass ItemMeta(ABCMeta):\n\n    def __new__(mcs, class_name, bases, attrs):\n        classcell = attrs.pop('__classcell__', None)\n        new_bases = tuple(base._class for base in bases if hasattr(base, '_class'))\n        _class = super(ItemMeta, mcs).__new__(mcs, 'x_' + class_name, new_bases, attrs)\n\n        fields = getattr(_class, 'fields', {})\n        new_attrs = {}\n        for n in dir(_class):\n            v = getattr(_class, n)\n            if isinstance(v, Field):\n                fields[n] = v\n            elif n in attrs:\n                new_attrs[n] = attrs[n]\n\n        new_attrs['fields'] = fields\n        new_attrs['_class'] = _class\n        if classcell is not None:\n            new_attrs['__classcell__'] = classcell\n        return super(ItemMeta, mcs).__new__(mcs, class_name, bases, new_attrs)\n\n\nclass DictItem(MutableMapping, BaseItem):\n\n    fields = {}\n\n    def __init__(self, *args, **kwargs):\n        self._values = {}\n        if args or kwargs:  # avoid creating dict for most common case\n            for k, v in six.iteritems(dict(*args, **kwargs)):\n                self[k] = v\n\n    def __getitem__(self, key):\n        return self._values[key]\n\n    def __setitem__(self, key, value):\n        if key in self.fields:\n            self._values[key] = value\n        else:\n            raise KeyError(\"%s does not support field: %s\" %\n                (self.__class__.__name__, key))\n\n    def __delitem__(self, key):\n        del self._values[key]\n\n    def __getattr__(self, name):\n        if name in self.fields:\n            raise AttributeError(\"Use item[%r] to get field value\" % name)\n        raise AttributeError(name)\n\n    def __setattr__(self, name, value):\n        if not name.startswith('_'):\n            raise AttributeError(\"Use item[%r] = %r to set field value\" %\n                (name, value))\n        super(DictItem, self).__setattr__(name, value)\n\n    def __len__(self):\n        return len(self._values)\n\n    def __iter__(self):\n        return iter(self._values)\n\n    __hash__ = BaseItem.__hash__\n\n    def keys(self):\n        return self._values.keys()\n\n    def __repr__(self):\n        return pformat(dict(self))\n\n    def copy(self):\n        return self.__class__(self)\n\n\n@six.add_metaclass(ItemMeta)\nclass Item(DictItem):\n    pass\n", "path": "scrapy/item.py"}], "after_files": [{"content": "\"\"\"\nScrapy Item\n\nSee documentation in docs/topics/item.rst\n\"\"\"\n\nfrom pprint import pformat\nfrom collections import MutableMapping\nfrom copy import deepcopy\n\nfrom abc import ABCMeta\nimport six\n\nfrom scrapy.utils.trackref import object_ref\n\n\nclass BaseItem(object_ref):\n    \"\"\"Base class for all scraped items.\"\"\"\n    pass\n\n\nclass Field(dict):\n    \"\"\"Container of field metadata\"\"\"\n\n\nclass ItemMeta(ABCMeta):\n\n    def __new__(mcs, class_name, bases, attrs):\n        classcell = attrs.pop('__classcell__', None)\n        new_bases = tuple(base._class for base in bases if hasattr(base, '_class'))\n        _class = super(ItemMeta, mcs).__new__(mcs, 'x_' + class_name, new_bases, attrs)\n\n        fields = getattr(_class, 'fields', {})\n        new_attrs = {}\n        for n in dir(_class):\n            v = getattr(_class, n)\n            if isinstance(v, Field):\n                fields[n] = v\n            elif n in attrs:\n                new_attrs[n] = attrs[n]\n\n        new_attrs['fields'] = fields\n        new_attrs['_class'] = _class\n        if classcell is not None:\n            new_attrs['__classcell__'] = classcell\n        return super(ItemMeta, mcs).__new__(mcs, class_name, bases, new_attrs)\n\n\nclass DictItem(MutableMapping, BaseItem):\n\n    fields = {}\n\n    def __init__(self, *args, **kwargs):\n        self._values = {}\n        if args or kwargs:  # avoid creating dict for most common case\n            for k, v in six.iteritems(dict(*args, **kwargs)):\n                self[k] = v\n\n    def __getitem__(self, key):\n        return self._values[key]\n\n    def __setitem__(self, key, value):\n        if key in self.fields:\n            self._values[key] = value\n        else:\n            raise KeyError(\"%s does not support field: %s\" %\n                (self.__class__.__name__, key))\n\n    def __delitem__(self, key):\n        del self._values[key]\n\n    def __getattr__(self, name):\n        if name in self.fields:\n            raise AttributeError(\"Use item[%r] to get field value\" % name)\n        raise AttributeError(name)\n\n    def __setattr__(self, name, value):\n        if not name.startswith('_'):\n            raise AttributeError(\"Use item[%r] = %r to set field value\" %\n                (name, value))\n        super(DictItem, self).__setattr__(name, value)\n\n    def __len__(self):\n        return len(self._values)\n\n    def __iter__(self):\n        return iter(self._values)\n\n    __hash__ = BaseItem.__hash__\n\n    def keys(self):\n        return self._values.keys()\n\n    def __repr__(self):\n        return pformat(dict(self))\n\n    def copy(self):\n        return self.__class__(self)\n\n    def deepcopy(self):\n        \"\"\"Return a `deep copy`_ of this item.\n\n        .. _deep copy: https://docs.python.org/library/copy.html#copy.deepcopy\n        \"\"\"\n        return deepcopy(self)\n\n\n@six.add_metaclass(ItemMeta)\nclass Item(DictItem):\n    pass\n", "path": "scrapy/item.py"}]}