ENH: Ensure that sys.path has the current directory in setup.py

[ikhramts]

Motivation

I tried to install the latest dev branch using pip in an embedded Python on Windows, and got error ModuleNotFoundError: No module named 'versioneer' in setup.py.

This is a typical error with embedded Python because it does not add the current directory to PYTHONPATH.

h5py fixed this issue two years ago by explicitly adding '' to sys.path in setup.py.

This PR makes the same change here.

How to test the behavior?

On Windows, using PowerShell

Before the change:

# Download and unzip embedded Python
> wget "https://www.python.org/ftp/python/3.9.6/python-3.9.6-embed-amd64.zip" -outfile "python.zip"
> Expand-Archive -Path python.zip -DestinationPath .\python

# Add site-packages to PYTHONPATH. 
# (Unfortunately we can't use this method to add the current dir)
> Add-Content -Path .\python\python39._pth -Value 'import site'

# Install PIP
> wget "https://bootstrap.pypa.io/get-pip.py" -outfile "get-pip.py"
> .\python\python.exe .\get-pip.py --no-warn-script-location
Collecting pip
  Using cached pip-21.2.4-py3-none-any.whl (1.6 MB)
Collecting setuptools
  Using cached setuptools-57.4.0-py3-none-any.whl (819 kB)
Collecting wheel
  Using cached wheel-0.37.0-py2.py3-none-any.whl (35 kB)
Installing collected packages: wheel, setuptools, pip
Successfully installed pip-21.2.4 setuptools-57.4.0 wheel-0.37.0

# Install PyNWB from the current dev branch:
> .\python\python.exe -m pip install https://github.com/NeurodataWithoutBorders/pynwb/archive/refs/heads/dev.zip --no-warn-script-location
Collecting https://github.com/NeurodataWithoutBorders/pynwb/archive/refs/heads/dev.zip
  Using cached https://github.com/NeurodataWithoutBorders/pynwb/archive/refs/heads/dev.zip
    ERROR: Command errored out with exit status 1:
     command: 'E:\Iouri_Temp\pynwb_test\python\python.exe' -c 'import io, os, sys, setuptools, tokenize; sys.argv[0] = '"'"'C:\\Users\\ikhramts\\AppData\\Local\\Temp\\pip-req-build-jc0j42u3\\setup.py'"'"'; __file__='"'"'C:\\Users\\ikhramts\\AppData\\Local\\Temp\\pip-req-build-jc0j42u3\\setup.py'"'"';f = getattr(tokenize, '"'"'open'"'"', open)(__file__) if os.path.exists(__file__) else io.StringIO('"'"'from setuptools import setup; setup()'"'"');code = f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' egg_info --egg-base 'C:\Users\ikhramts\AppData\Local\Temp\pip-pip-egg-info-eliwd_ot'
         cwd: C:\Users\ikhramts\AppData\Local\Temp\pip-req-build-jc0j42u3\
    Complete output (5 lines):
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "C:\Users\ikhramts\AppData\Local\Temp\pip-req-build-jc0j42u3\setup.py", line 5, in <module>
        import versioneer
    ModuleNotFoundError: No module named 'versioneer'
    ----------------------------------------
WARNING: Discarding https://github.com/NeurodataWithoutBorders/pynwb/archive/refs/heads/dev.zip. Command errored out with exit status 1: python setup.py egg_info Check the logs for full command output.
ERROR: Command errored out with exit status 1: python setup.py egg_info Check the logs for full command output.

After the change, everything installs correctly:

# ... Install Python, PIP ...

# Install PyNWB from the branch with the fix:
> .\python\python.exe -m pip install https://github.com/ikhramts/pynwb/archive/refs/heads/setup-py-add-current-dir.zip --no-warn-script-location
Collecting https://github.com/ikhramts/pynwb/archive/refs/heads/setup-py-add-current-dir.zip
  Using cached https://github.com/ikhramts/pynwb/archive/refs/heads/setup-py-add-current-dir.zip
Collecting h5py<4,>=2.9
  Using cached h5py-3.3.0-cp39-cp39-win_amd64.whl (2.8 MB)
Collecting hdmf<4,>=3.1.1
  Using cached hdmf-3.1.1-py3-none-any.whl (173 kB)
Collecting numpy<1.22,>=1.16
  Using cached numpy-1.21.1-cp39-cp39-win_amd64.whl (14.0 MB)
Collecting pandas<2,>=1.0.5
  Using cached pandas-1.3.1-cp39-cp39-win_amd64.whl (10.4 MB)
Collecting python-dateutil<3,>=2.7
  Using cached python_dateutil-2.8.2-py2.py3-none-any.whl (247 kB)
Requirement already satisfied: setuptools in e:\iouri_temp\pynwb_test\python\lib\site-packages (from pynwb==0+unknown) (57.4.0)
Collecting scipy<2,>=1.1
  Using cached scipy-1.7.1-cp39-cp39-win_amd64.whl (33.8 MB)
Collecting ruamel.yaml<1,>=0.16
  Using cached ruamel.yaml-0.17.10-py3-none-any.whl (108 kB)
Collecting jsonschema<4,>=2.6.0
  Using cached jsonschema-3.2.0-py2.py3-none-any.whl (56 kB)
Collecting attrs>=17.4.0
  Using cached attrs-21.2.0-py2.py3-none-any.whl (53 kB)
Collecting six>=1.11.0
  Using cached six-1.16.0-py2.py3-none-any.whl (11 kB)
Collecting pyrsistent>=0.14.0
  Using cached pyrsistent-0.18.0-cp39-cp39-win_amd64.whl (62 kB)
Collecting pytz>=2017.3
  Using cached pytz-2021.1-py2.py3-none-any.whl (510 kB)
Collecting ruamel.yaml.clib>=0.1.2
  Using cached ruamel.yaml.clib-0.2.6-cp39-cp39-win_amd64.whl (118 kB)
Building wheels for collected packages: pynwb
  Building wheel for pynwb (setup.py) ... done
  Created wheel for pynwb: filename=pynwb-0+unknown-py2.py3-none-any.whl size=85363 sha256=d112ae47203c387f8c11af8d9333aa0e5ee337357461c44af80814f812f22666
  Stored in directory: c:\users\ikhramts\appdata\local\pip\cache\wheels\60\fe\62\2f2fe5e57aa49bc503a5f1342ef997f95e989a538028df62ce
Successfully built pynwb
Installing collected packages: six, ruamel.yaml.clib, pytz, python-dateutil, pyrsistent, numpy, attrs, scipy, ruamel.yaml, pandas, jsonschema, h5py, hdmf, pynwb
Successfully installed attrs-21.2.0 h5py-3.3.0 hdmf-3.1.1 jsonschema-3.2.0 numpy-1.21.1 pandas-1.3.1 pynwb-0+unknown pyrsistent-0.18.0 python-dateutil-2.8.2 pytz-2021.1 ruamel.yaml-0.17.10 ruamel.yaml.clib-0.2.6 scipy-1.7.1 six-1.16.0

Checklist

• Did you update CHANGELOG.md with your changes?
• Have you checked our Contributing document?
• Have you ensured the PR clearly describes the problem and the solution?
• Is your contribution compliant with our coding style? This can be checked running flake8 from the source directory.
• Have you checked to ensure that there aren't other open Pull Requests for the same change?
• Have you included the relevant issue number using "Fix #XXX" notation where XXX is the issue number? By including "Fix #XXX" you allow GitHub to close issue #XXX when the PR is merged.

[rly]

Thanks for the PR @ikhramts !