Did you take a call to resign after the policy change or before?
What is the specific problem for you in serving 45 days? Is your present employer asking you to come early to join?
Speak to your HR if you want a waiver as the policy is a recent modified one, may be he can take it up and relive you earlier.
Do not try to put yourself in a tricky stage,having been there for a considerable period in work and convince the HR for getting a soft exit.
18th November 2017 From India, Hyderabad