To avoid accidents, consider removing push permissions on your upstream from your local repository.
Go to \path-to\osparc-simcore-fork
and you should have a clean repo
git status
On branch master
Your branch is up-to-date with 'origin/master'.
nothing to commit, working directory clean
List remotes
git remote -vv
origin git@github.com:USER/osparc-simcore.git (fetch)
origin git@github.com:USER/osparc-simcore.git (push)
Setup upstream
git remote add upstream git@github.com:ITISFoundation/osparc-simcore.git
Overwrite push to disallow access
git remote set-url upstream --push "You_shall_not_push_but_use_PR_instead"
Final result will look similar to the following
git remote -vv
origin git@github.com:USER/osparc-simcore-forked.git (fetch)
origin git@github.com:USER/osparc-simcore-forked.git (push)
upstream git@github.com:ITISFoundation/osparc-simcore.git (fetch)
upstream You_shall_not_push_but_use_PR_instead (push)