Error when stacking using pip-accel instead of pip

[FedericoRessi]

Commit-Id: 188a66c65cc43d3850656c948fb36dfa4197df3f This is a copy of the issue reported on pip-accel: https://github.com/paylogic/pip-accel/issues/63

I am trying to accelerate devstack execution using pip_accell. After forcing devstack to use pip-accell I had below error as soon as devstack tries to install/update setuptools package.

The failing command line is this:

sudo -H pip-accel install -v -c upper-constraints.txt -U setuptools

I have attached the whole error log and upper-constraints.txt file.

• upper-constraints.txt
• error.txt

Produced error is this:

2015-12-28 09:52:23 control pip_accel.cli[19019] ERROR Caught unhandled exception!
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/pip_accel/cli.py", line 57, in main
    accelerator.install_from_arguments(arguments)
  File "/usr/local/lib/python2.7/dist-packages/pip_accel/__init__.py", line 234, in install_from_arguments
    have_wheels = any(req.is_wheel for req in requirements)
  File "/usr/local/lib/python2.7/dist-packages/pip_accel/__init__.py", line 234, in <genexpr>
    have_wheels = any(req.is_wheel for req in requirements)
  File "/usr/local/lib/python2.7/dist-packages/cached_property.py", line 26, in __get__
    value = obj.__dict__[self.func.__name__] = self.func(obj)
  File "/usr/local/lib/python2.7/dist-packages/pip_accel/req.py", line 167, in is_wheel
    probably_sdist = os.path.isfile(os.path.join(self.source_directory, 'setup.py'))
  File "/usr/lib/python2.7/posixpath.py", line 77, in join
    elif path == '' or path.endswith('/'):
AttributeError: 'NoneType' object has no attribute 'endswith'