backtrace when using in new projects

[Robert Collins]

$ tox
GLOB sdist-make: /home/robertc/work/bindep/setup.py
ERROR: invocation failed, logfile: /home/robertc/work/bindep/.tox/log/tox-0.log
ERROR: actionid=tox
msg=packaging
cmdargs=['/usr/bin/python', local('/home/robertc/work/bindep/setup.py'), 'sdist', '--formats=zip', '--dist-dir', local('/home/robertc/work/bindep/.tox/dist')]
env=None
setup hook pbr.hooks.setup_hook raised exception: 'NoneType' object has no attribute 'replace'

Traceback (most recent call last):
  File "/home/robertc/work/bindep/d2to1-0.2.10-py2.7.egg/d2to1/util.py", line 182, in cfg_to_args
    hook_fn(config)
  File "/home/robertc/work/bindep/pbr-0.5.14-py2.7.egg/pbr/hooks.py", line 39, in setup_hook
    metadata.get('version', None))
  File "/home/robertc/work/bindep/pbr-0.5.14-py2.7.egg/pbr/packaging.py", line 489, in get_version
    version = _get_version_from_git(pre_version)
  File "/home/robertc/work/bindep/pbr-0.5.14-py2.7.egg/pbr/packaging.py", line 450, in _get_version_from_git
    "git --git-dir=" + git_dir + " describe --always").replace(
AttributeError: 'NoneType' object has no attribute 'replace'

error in setup command: Error parsing /home/robertc/work/bindep/setup.cfg: SystemExit: 1

ERROR: FAIL could not package project
(bindep-2.7)robertc@lifelesshp:~/work/bindep$ git describe --always
fatal: Not a valid object name HEAD

[Robert Collins (lifeless)]

Fixed by the semver work