pullrequests: refactor default title code This refactoring simply emphasizes that the origin reference used to generate the default title is not always the same as the one actually used to create the pull request; for PRs not from a branch head, the branch name is stored so it can be used for creating new iterations.

[tox]
minversion = 1.8
envlist = py{26,27}-pytest

[testenv]
setenv =
    PYTHONHASHSEED = 0
deps =
    -r{toxinidir}/dev_requirements.txt
    py26-pytest: unittest2
    python-ldap
    python-pam
commands =
    pytest: py.test {posargs}