Password validator not working on changing password for first time (HorizonPasswordValidator)

Issue

We have openstack configured with this parameters:
"""
KeystoneChangePasswordUponFirstUse: True
HorizonPasswordValidator: '^.{8,30}$'
"""
While creating new user password validator works fine. When we login with new user for the first time, it ask to change the password. But password validator doesn't work here and we can create password with less than 8 characters.