Major rewrite of project

[Tomas Korbar]

Hi,
I would like to ask you a question. If upstream of your package does major
rewrite of it, then what is the proper process to rebase such package? I'm
maintainer of cheat [0] which has been rewritten in go. I suppose i need a
new package review but then if the new spec passes review am i supposed to
replace the spec of old package entirely or preserve changelog and add new
entry with description of what happened + link to the review?
[0] - https://github.com/cheat/cheat