`pkg_resources` fails to find `gcloud` on the first run of an env

[dhermes]

@jonparrott I don't see this as a pressing issue, so if you don't know, just close it out.

Why does pkg_resources fail to find gcloud on the first run of an env? To complicate things, this doesn't happen when a new env. is created on Travis.

---

Here is an example

$ rm -fr .tox/docs
$ tox -e docs
GLOB sdist-make: .../gcloud-python/setup.py
docs create: .../gcloud-python/.tox/docs
docs installdeps: nose, nose-exclude, grpcio >= 1.0rc1, google-gax >= 0.12.3, < 0.13dev, gax-google-pubsub-v1 >= 0.8.0, < 0.9dev, grpc-google-pubsub-v1 >= 0.8.0, < 0.9dev, gax-google-logging-v2 >= 0.8.0, < 0.9dev, grpc-google-logging-v2 >= 0.8.0, < 0.9dev, nose, nose-exclude, grpcio >= 1.0rc1, google-gax >= 0.12.3, < 0.13dev, gax-google-pubsub-v1 >= 0.8.0, < 0.9dev, grpc-google-pubsub-v1 >= 0.8.0, < 0.9dev, gax-google-logging-v2 >= 0.8.0, < 0.9dev, grpc-google-logging-v2 >= 0.8.0, < 0.9dev, Sphinx, sphinx_rtd_theme
docs inst: .../gcloud-python/.tox/dist/gcloud-0.18.0.zip
docs installed: alabaster==0.7.9,Babel==2.3.4,docutils==0.12,enum34==1.1.6,future==0.15.2,futures==3.0.5,gax-google-logging-v2==0.8.1,gax-google-pubsub-v1==0.8.1,gcloud==0.18.0,google-gax==0.12.5,googleapis-common-protos==1.2.0,grpc-google-logging-v2==0.8.1,grpc-google-pubsub-v1==0.8.1,grpcio==1.0.0,httplib2==0.9.2,imagesize==0.7.1,Jinja2==2.8,MarkupSafe==0.23,nose==1.3.7,nose-exclude==0.4.1,oauth2client==3.0.0,ply==3.8,protobuf==3.0.0,pyasn1==0.1.9,pyasn1-modules==0.0.8,Pygments==2.1.3,pytz==2016.6.1,rsa==3.4.2,six==1.10.0,snowballstemmer==1.2.1,Sphinx==1.4.6,sphinx-rtd-theme==0.1.9
docs runtests: PYTHONHASHSEED='2428814037'
docs runtests: commands[0] | python -c import shutil; shutil.rmtree('docs/_build', ignore_errors=True)
docs runtests: commands[1] | sphinx-build -W -b html -d docs/_build/doctrees docs docs/_build/html
Running Sphinx v1.4.6
making output directory...

Exception occurred:
  File ".../gcloud-python/.tox/docs/local/lib/python2.7/site-packages/pkg_resources/__init__.py", line 853, in resolve
    raise DistributionNotFound(req, requirers)
DistributionNotFound: The 'gcloud' distribution was not found and is required by the application
The full traceback has been saved in /tmp/sphinx-err-SrV6xS.log, if you want to report the issue to the developers.
Please also report this if it was a user error, so that a better error message can be provided next time.
A bug report can be filed in the tracker at <https://github.com/sphinx-doc/sphinx/issues>. Thanks!
ERROR: InvocationError: '.../gcloud-python/.tox/docs/bin/sphinx-build -W -b html -d docs/_build/doctrees docs docs/_build/html'
___________________________________________________________________ summary ___________________________________________________________________
ERROR:   docs: commands failed

[theacodes]

I actually don't know. ¯_(ツ)_/¯

My first guess was that gcloud wasn't installed, but it's installed on line 6.

You could try manually stepping into tox's virtualenv for the docs and seeing what's up?

[duggelz]

Without looking at the code, a number of pieces of pkg_resources don't behave entirely correctly for namespace packages, and whether a package is a namespace package depends very delicately on sys.path, PYTHONPATH, .pth files, and most relevantly, any __init__.pyc's that might only be generated after the first (or Nth) time something is imported.

[theacodes]

pkg_resources works fine for ns packages and is in fact the mechanism by which we even have them. I'm not sure what this issue was, but it hasn't cropped up again since we switched to nox.

[duggelz]

You're right, I'm thinking of pkgutil, which I have a couple of open bugs for.