I’m not sure why people do this if you’re about to start a system re-write. Especially if you are also re-writing an application in a new language. Maybe you are updating from VB6 to a .NET application.
Why lob all of this new spangly beautiful code into the same old tired repository?
It gets confusing for anyone coming into the team cold and trying to get up to speed. It gets confusing to know what 3rd party binaries are old and which are new.
You’ll also end up with a potentially MASSIVE repository that contains stuff you need and stuff you no longer care about …
Create a new repository people!!