old_contents: # Copyright (c) 2015, Frappe Technologies Pvt. Ltd. and Contributors
  # License: GNU General Public License v3. See license.txt
  
  from __future__ import unicode_literals
  import frappe
  from frappe import _
  
  
  from frappe.utils.nestedset import NestedSet
  class CustomerGroup(NestedSet):
  	nsm_parent_field = 'parent_customer_group';
  
  	def on_update(self):
  		self.validate_name_with_customer()
  		super(CustomerGroup, self).on_update()
  		self.validate_one_root()
  
  	def validate_name_with_customer(self):
  		if frappe.db.exists("Customer", self.name):
  			frappe.msgprint(_("An Customer exists with same name"), raise_exception=1)
  
  def get_parent_customer_groups(customer_group):
  	lft, rgt = frappe.db.get_value("Customer Group", customer_group, ['lft', 'rgt'])
  
  	return frappe.db.sql("""select name from `tabCustomer Group`
  		where lft <= %s and rgt >= %s
  		order by lft asc""", (lft, rgt), as_dict=True)
new_contents: # Copyright (c) 2015, Frappe Technologies Pvt. Ltd. and Contributors
  # License: GNU General Public License v3. See license.txt
  
  from __future__ import unicode_literals
  import frappe
  from frappe import _
  
  
  from frappe.utils.nestedset import NestedSet
  class CustomerGroup(NestedSet):
  	nsm_parent_field = 'parent_customer_group';
  
  	def on_update(self):
  		self.validate_name_with_customer()
  		super(CustomerGroup, self).on_update()
  		self.validate_one_root()
  
  	def validate_name_with_customer(self):
  		if frappe.db.exists("Customer", self.name):
  			frappe.msgprint(_("A customer with the same name already exists"), raise_exception=1)
  
  def get_parent_customer_groups(customer_group):
  	lft, rgt = frappe.db.get_value("Customer Group", customer_group, ['lft', 'rgt'])
  
  	return frappe.db.sql("""select name from `tabCustomer Group`
  		where lft <= %s and rgt >= %s
  		order by lft asc""", (lft, rgt), as_dict=True)
  
subject: Update customer_group.py (#11270)