This is totally for me in the future because I always bloody forget when switching to a Bitbucket project:
Bitbucket (creates the branch remotely, ready for you to make a pull request and add reviewers):
git push -u $(git remote) cool_branch_name
Gerrit (creates a review against the project_ci branch, whatever that is, ready for you to add reviewers):
git push $(git remote) HEAD:refs/for/project_ci
