Refactor git branching If a checkout is already available and the branch is changed in the config git command would always fail because it doesn't know the branch to track. Therefore always check if the branch is locally available and if not checkout the remote branch

# jobdaemon.cfg examlpe
# back tasks of treepkg
/path/to/treepkg1/bin/publishdebianpackages.py
/path/to/treepkg2/bin/publishdebianpackages.py
# tasks to run synchronously
BLOCKER: update-apt-files.sh