That example is too simplistic, it's called legacy systems and not legacy software. If you upgrade your tool-chain you include git. Really no one is interested

That example is too simplistic, it's called legacy systems and not legacy software. If you upgrade your tool-chain you include git. Really no one is interested in upgrading 'just' git, make a package out of it (new compiler, new CI, new testing, new version controll..fuzz etc) call the project "sustainable nextgen tool-chain...short SuNeTuCha" and sell it to the management like that.