As you may have already noticed, OregonCore moved from Mercurial and Bitbucket to Git and Github.
We encourage you to first read this guide entirely and then start following its steps.
This is essential, and almost everything that you need to do.
You should already be fine, but in case anything goes wrong, you can roll back and start over again.
Let's say that you're copy was in 'oregoncore' directory, in that case rename it to 'oregoncore_backup' or something like that.
Get new tools to work with git and clone a new repo, this time from git. Clone it to directory that was your original (in our case 'oregoncore').
Please refer to installation guide:
If you're not using automatic updater, first apply all new database updates. If you haven't yet, stop your server and run the new one you've just built.
If you encounter any difficulties please come on forums and let us know.
If you followed this guide correctly, we will surely find a solution.