Duplicate transition on customer portal when Resolution field is updated

Issue Summary

Duplicate transition on customer portal when Resolution field is updated using a post function or transition screen

Steps to Reproduce

1. Create a workflow with the status To do > In progress > Done > To do
2. Add a post function to set the Resolution as Complete when the issue moves from In progress > Done
3. Add a post function to clear the Resolution when the issue moves from Done > To do
4. Create an issue and transition it from 
   To do > In progress 
   In progress > Done (post function set the resolution as Complete)
   Done > In progress (post function clears the resolution) 

Expected Results

All the 3 transitions are displayed exactly once on the customer portal

Actual Results

The last 2 transition appears twice on the customer portal along with the Resolution set 

Your request status has changed to In progress
Your request status has changed to Done with resolution Complete.
Your request status has changed to Done with resolution Complete. 
Your request status has changed to In progress
Your request status has changed to In progres

Workaround

Currently, there is no known workaround for this behavior. A workaround will be added here when available