Can't install via archive file distributed on pypi

[calebrob6]

Describe the bug

The setup.py script uses build_helpers/ however build_helpers/ isn't included in the pypi code archive, so running python setup.py sdist from that archive isn't possible.

Expected behavior
Expect to be able to install via the code archive uploaded to pypi.

[Jasha10]

Thanks for the report. I can reproduce the issue:

$ # Download the archive linked from https://pypi.org/project/omegaconf/#files
$ wget https://files.pythonhosted.org/packages/db/fa/dfcbaffd016aeedd20f6ce800de171e13128490f767e8f68ec3baab21eaa/omegaconf-2.1.0.tar.gz
$ tar -xzf omegaconf-2.1.0.tar.gz
$ cd omegaconf-2.1.0/
$ pip install .
Processing /Users/jasha10/tmp/omegaconf-2.1.0
...
  Installing build dependencies ... done
  Getting requirements to build wheel ... error
  ERROR: Command errored out with exit status 1:
   command: /Users/jasha10/miniconda3/envs/tmp/bin/python /Users/jasha10/miniconda3/envs/tmp/lib/python3.9/site-packages/pip/_vendor/pep517/in_process/_in_process.py get_requires_for_build_wheel /var/folders/6r/93zx8_1s4jxg484fcjjzgjp40000gn/T/tmpok_6xgs6
       cwd: /private/var/folders/6r/93zx8_1s4jxg484fcjjzgjp40000gn/T/pip-req-build-6jx88eo9
  Complete output (18 lines):
  Traceback (most recent call last):
...
    File "setup.py", line 16, in <module>
      from build_helpers.build_helpers import (
  ModuleNotFoundError: No module named 'build_helpers'
...

This issue does not occur if I download the files directly from github.
The difference is that the build_helpers folder is included in the repository downloaded from github, but build_helpers is not present in the .tar.gz file I found on pypi.

[Jasha10]

This is closed in the new OmegaConf 2.1.1 release

$ wget https://files.pythonhosted.org/packages/91/80/c9268fedb0d63ddf7dfa4352070f8cfecf2b0443df7737462c3ab0437c11/omegaconf-2.1.1.tar.gz
...
$ tar -xzf omegaconf-2.1.1.tar.gz
$ cd omegaconf-2.1.1/
$ pip install .
...
Successfully installed PyYAML-5.4.1 antlr4-python3-runtime-4.8 omegaconf-2.1.1