rerun command requested

What is the status of the "rerun" command in LAMMPS?

I am referring to the "rerun" command discussed here:

Can you post what C++ code you have, even if it's difficult to use?

[This command would be very valuable for calculating free energy
differences (solvation, docking, etc..). Several analysis tools
(including several versions of "WHAM") require the user to be able to
simulate a system using one force field, and recalculate the energies
of the old trajectory using a different force field. The "rerun"
command would be one way to do this elegantly. Selfishly speaking, I
really need this, but I guess I can write an external bash script to
process one snapshot at a time.]

Tim was working on it ... he can respond if
he has something ... I had preliminary code but
it was not to the point of working.