Remove validation "An Item Group exists with same name, please change the item name or rename the item group"

[anandpdoshi]

Traceback (innermost last):
  File "/home/frappe/press/benches/1601271005/apps/frappe/frappe/desk/page/setup_wizard/setup_wizard.py", line 28, in setup_complete
    frappe.get_attr(method)(args)
  File "/home/frappe/press/benches/1601271005/apps/erpnext/erpnext/setup/setup_wizard/setup_wizard.py", line 32, in setup_complete
    create_items(args)
  File "/home/frappe/press/benches/1601271005/apps/erpnext/erpnext/setup/setup_wizard/setup_wizard.py", line 331, in create_items
    "default_warehouse": default_warehouse
  File "/home/frappe/press/benches/1601271005/apps/frappe/frappe/model/document.py", line 211, in insert
    self.run_post_save_methods()
  File "/home/frappe/press/benches/1601271005/apps/frappe/frappe/model/document.py", line 613, in run_post_save_methods
    self.run_method("on_update")
  File "/home/frappe/press/benches/1601271005/apps/frappe/frappe/model/document.py", line 557, in run_method
    return Document.hook(fn)(self, *args, **kwargs)
  File "/home/frappe/press/benches/1601271005/apps/frappe/frappe/model/document.py", line 712, in composer
    return composed(self, method, *args, **kwargs)
  File "/home/frappe/press/benches/1601271005/apps/frappe/frappe/model/document.py", line 695, in runner
    add_to_return_value(self, fn(self, *args, **kwargs))
  File "/home/frappe/press/benches/1601271005/apps/frappe/frappe/model/document.py", line 551, in 
    fn = lambda self, *args, **kwargs: getattr(self, method)(*args, **kwargs)
  File "/home/frappe/press/benches/1601271005/apps/erpnext/erpnext/stock/doctype/item/item.py", line 89, in on_update
    self.validate_name_with_item_group()
  File "/home/frappe/press/benches/1601271005/apps/erpnext/erpnext/stock/doctype/item/item.py", line 444, in validate_name_with_item_group
    frappe.throw(_("An Item Group exists with same name, please change the item name or rename the item group"))
  File "/home/frappe/press/benches/1601271005/apps/frappe/frappe/__init__.py", line 262, in throw
    msgprint(msg, raise_exception=exc)
  File "/home/frappe/press/benches/1601271005/apps/frappe/frappe/__init__.py", line 255, in msgprint
    _raise_exception()
  File "/home/frappe/press/benches/1601271005/apps/frappe/frappe/__init__.py", line 240, in _raise_exception
    raise raise_exception, encode(msg)
 ValidationError:

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To Do:

• Fix tree view generation in reports that have both Item Group and Item