What Heroku mean about " Don't forget to update git remotes for all other local checkouts of the app."?

I don't know Heroku, specifically, but I'm pretty good with git.

If I clone a git repo, that's a "local checkout," in Heroku's words. If you clone the same git repo, that's another local checkout. Now you and I each have a local checkout that points back to the original repo...the "remote."

If some third person changes the name of the original repo, which also changes the repo's URL, suddenly you and I can no longer push to or pull from the remote, because our local clones still point to the old URL, which is no longer valid. So we need to do this:

% git remote set-url [new URL]

(Here are more details on updating the remote's URL.) In practice, if the repo is publically accessible, you might not have any information about local checkouts beyond your own. If that's the case...there's nothing you can do, so don't sweat it unless someone gets in touch with you.