Python 2 builds breaking pybids

[effigies]

Just to let you know, some time between Oct 10 and 17, the Python 2 nightly build started producing the following failure in pybids:

ImportError while importing test module '/home/travis/build/bids-standard/pybids/bids/analysis/tests/test_analysis.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
venv/lib/python2.7/site-packages/six.py:709: in exec_
    exec("""exec _code_ in _globs_, _locs_""")
bids/analysis/tests/test_analysis.py:2: in <module>
    from bids.analysis import Analysis
bids/__init__.py:4: in <module>
    from .analysis import Analysis
bids/analysis/__init__.py:1: in <module>
    from .analysis import Analysis
bids/analysis/analysis.py:2: in <module>
    from bids.layout import BIDSLayout
bids/layout/__init__.py:1: in <module>
    from .layout import BIDSLayout
bids/layout/layout.py:5: in <module>
    from .validation import BIDSValidator
bids/layout/validation.py:6: in <module>
    import pandas as pd
venv/lib/python2.7/site-packages/pandas/__init__.py:35: in <module>
    "the C extensions first.".format(module))
E   ImportError: C extension: No module named enum not built. If you want to import pandas from the source directory, you may need to run 'python setup.py build_ext --inplace --force' to build the C extensions first.

As well as a number of similar errors. See, e.g., Travis builds #792.4 or #817.4.

This only occurs with --pre builds using the ManyLinux repository. Depending on the exact timing of the builds, it looks like it could have been caused by either of the last two commits: 131a2b7 or 93b492a

Related discussion: bids-standard/pybids#276

[effigies]

Sorry to pester, but does anybody have information on this? We're having to ignore errors in Python2+nightly altogether, in order to have a reliable indicator of other errors, which means upcoming changes in Pandas that only affect Python 2 are going to be completely missed until they're released.

[jreback]

have u seen: https://travis-ci.org/MacPython/pandas-wheels/builds

our nightly builds have been working for quite some time (small hiccup on 32 but for a little)

[effigies]

I'm not sure what to take away from that. We're still unable to use the package that is produced.

See, for example: https://travis-ci.org/bids-standard/pybids/jobs/465013222

[jreback]

you have a file named enum.py which is shadowing a built in module - not a great idea

[effigies]

Running python -v -m bids.analysis, I'm unable to see evidence of any enum.py except the builtin module, and searching through the file trees for pybids and our main dependencies, I can't see an enum.py anywhere. Sorry if I'm being dense...

[jreback]

then no idea

[effigies]

From playing around a bit more, it seems to be that Pandas uses Enum, but doesn't require enum34 for Python versions <3.4. It looks like this dependency was introduced in pandas-dev/pandas#22802.

It wasn't erroring out in your tests, apparently, because hypothesis depends on it:

9103 Collecting enum34; python_version == "2.7" (from hypothesis)

Testing in bids-standard/pybids#315 to see if this clears up all of the errors.

[jreback]

hmm interesting can u make an issue on the main pandas repo

[effigies]

Was just about to submit a PR. Do you prefer to have an issue first?

[jreback]

what u did is fine thanks