The problem is that you haven't described why Launchpad should be involved in your pull request at all. We don't host git repositories, so you'll need to push the branch somewhere else in order to submit a pull request. It's easier to use bzr-git to do this than it is to push to Launchpad, and then request Launchpad to push to some other site. Since the other site would require credentials, you'd also need to provide Launchpad with your login/password to the other site, or at least set up an OAuth token on that other site that allowed Launchpad to push for you.
The problem is that you haven't described why Launchpad should be involved in your pull request at all. We don't host git repositories, so you'll need to push the branch somewhere else in order to submit a pull request. It's easier to use bzr-git to do this than it is to push to Launchpad, and then request Launchpad to push to some other site. Since the other site would require credentials, you'd also need to provide Launchpad with your login/password to the other site, or at least set up an OAuth token on that other site that allowed Launchpad to push for you.