generating hooks needs to be thread/process safe

If not this might happen:

INFO:pbuilderjenkins:Setting up hooks
INFO:pbuilderjenkins:Adding D01apt_update hook ("apt-get update" call)
DEBUG:pbuilderjenkins:Temporary hooks directory: /tmp/tmpW81E8s
DEBUG:pbuilderjenkins:Creating hook from D09add_ppa~ubuntu-unity~daily-build
DEBUG:pbuilderjenkins:Parsed into ubuntu-unity, daily-build
Traceback (most recent call last):
  File "/usr/bin/pbuilderjenkins", line 99, in <module>
    builder.execute_build(hooks=args.hook_list)
  File "/usr/lib/python2.7/dist-packages/pbuilderjenkins/pbuilderjenkins.py", line 338, in execute_build
    hooks_dir = self.hooks_setup(hooks)
  File "/usr/lib/python2.7/dist-packages/pbuilderjenkins/pbuilderjenkins.py", line 176, in hooks_setup
    hook_provision(self.hooks_repo_dir, hook_wishlist, hooks_dir)
  File "/usr/lib/python2.7/dist-packages/pbuilderjenkins/pbuilderjenkins.py", line 83, in hook_provision
    create_ppa_hook(hook, parsed_hook, hooks_dir)
  File "/usr/lib/python2.7/dist-packages/pbuilderjenkins/hookshelper.py", line 69, in create_ppa_hook
    archive = get_ppa(person, ppa_name)
  File "/usr/lib/python2.7/dist-packages/pbuilderjenkins/hookshelper.py", line 40, in get_ppa
    launchpad = _get_launchpad()
  File "/usr/lib/python2.7/dist-packages/pbuilderjenkins/hookshelper.py", line 32, in _get_launchpad
    authorization_engine=authorization_engine)
  File "/usr/lib/python2.7/dist-packages/launchpadlib/launchpad.py", line 539, in login_with
    credential_save_failed, version)
  File "/usr/lib/python2.7/dist-packages/launchpadlib/launchpad.py", line 359, in _authorize_token_and_login
    service_root, cache, timeout, proxy_info, version)
  File "/usr/lib/python2.7/dist-packages/launchpadlib/launchpad.py", line 198, in __init__
    credentials, service_root, cache, timeout, proxy_info, version)
  File "/usr/lib/python2.7/dist-packages/lazr/restfulclient/resource.py", line 465, in __init__
    self._browser.get(root_resource), 'application/json')
  File "/usr/lib/python2.7/dist-packages/wadllib/application.py", line 363, in bind
    representation_definition)
  File "/usr/lib/python2.7/dist-packages/wadllib/application.py", line 300, in __init__
    _make_unicode(representation))
  File "/usr/lib/python2.7/dist-packages/simplejson/__init__.py", line 413, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python2.7/dist-packages/simplejson/decoder.py", line 405, in decode
    raise JSONDecodeError("Extra data", s, end, len(s))