Check for scripts directory in get_script_from_egg

[yolken]

Background

Some eggs (e.g., those for v0.13 of the Flask-Cache library) don't have scripts. This can cause problems when they are bundled in a pex with another library and the pex entrypoint is set to a (valid) script in the latter.

Depending on the order in which the libraries are searched for the script, it's possible to get errors like the following when executing the pex:

Traceback (most recent call last):
  File ".bootstrap/_pex/pex.py", line 326, in execute
  File ".bootstrap/_pex/pex.py", line 258, in _wrap_coverage
  File ".bootstrap/_pex/pex.py", line 290, in _wrap_profiling
  File ".bootstrap/_pex/pex.py", line 372, in _execute
  File ".bootstrap/_pex/pex.py", line 405, in execute_script
  File ".bootstrap/_pex/finders.py", line 286, in get_script_from_distributions
  File ".bootstrap/_pex/finders.py", line 270, in get_script_from_distribution
  File ".bootstrap/_pex/finders.py", line 243, in get_script_from_egg
  File ".bootstrap/pkg_resources/__init__.py", line 1480, in metadata_listdir
  File ".bootstrap/pkg_resources/__init__.py", line 1566, in _listdir
OSError: [Errno 2] No such file or directory: '/Users/ben_yolken/.pex/install/Flask_Cache-0.13.1-py2.7.egg.57c4257163765d8d5a7be01c059b291c0880ed47/Flask_Cache-0.13.1-py2.7.egg/EGG-INFO/scripts'

The fix is to check in get_script_from_egg whether the scripts directory exists before calling metadata_listdir.

Content

• Check for scripts directory in get_script_from_egg

[kwlzn]

thanks for the bugfix - lgtm.

while you're in here, how would you feel about adding a quick unit or integration test to help pin this behavior down?

[yolken]

@kwlzn Added a small test for the Flask-Cache case. Thanks.

[kwlzn]

lgtm, thanks for the PR!