race condition creating a branch for the pull request

I released two packages at the same time (running bloom-release from two separate shells). Both generated pull requests "shared" the same branch in my forked rosdistro repo.

The relevant bloom logs: https://gist.github.com/dirk-thomas/5937912 https://gist.github.com/dirk-thomas/5937914

You could use the rosdistro and package name in the branch name to reduce the chances of collisions.