$ nix/store/9vgdq8aivsmkbzszapgq8q0qp9y1ssd9-script/bin/output
Traceback (most recent call last):
  File "/nix/store/9vgdq8aivsmkbzszapgq8q0qp9y1ssd9-script/bin/output", line 2, in <module>
    import numpy as np
  File "/srv/current/stack/lib/python2.7/site-packages/numpy/__init__.py", line 180, in <module>
    from . import add_newdocs
  File "/srv/current/stack/lib/python2.7/site-packages/numpy/add_newdocs.py", line 13, in <module>
    from numpy.lib import add_newdoc
  File "/srv/current/stack/lib/python2.7/site-packages/numpy/lib/__init__.py", line 8, in <module>
    from .type_check import *
  File "/srv/current/stack/lib/python2.7/site-packages/numpy/lib/type_check.py", line 11, in <module>
    import numpy.core.numeric as _nx
  File "/srv/current/stack/lib/python2.7/site-packages/numpy/core/__init__.py", line 57, in <module>
    from numpy.testing import Tester
  File "/srv/current/stack/lib/python2.7/site-packages/numpy/testing/__init__.py", line 14, in <module>
    from .utils import *
  File "/srv/current/stack/lib/python2.7/site-packages/numpy/testing/utils.py", line 15, in <module>
    from tempfile import mkdtemp
  File "/nix/store/3n3r10921c0mzfrq64hc4m2jzjk13qpr-python-2.7.13/lib/python2.7/tempfile.py", line 32, in <module>
    import io as _io
  File "/nix/store/3n3r10921c0mzfrq64hc4m2jzjk13qpr-python-2.7.13/lib/python2.7/io.py", line 51, in <module>
    import _io
ImportError: /nix/store/3n3r10921c0mzfrq64hc4m2jzjk13qpr-python-2.7.13/lib/python2.7/lib-dynload/_io.so: undefined symbol: _PyCodecInfo_GetIncrementalEncoder