Parallel test fails if tblib is not installed.

[user0007]

The error occurs when NoSuchElementException (selenium) exception is raised:

test_changing_password (apps.users.tests.test_admin.UserAdminLiveServer) failed:

    NoSuchElementException()

Unfortunately, tracebacks cannot be pickled, making it impossible for the
parallel test runner to handle this exception cleanly.

In order to see the traceback, you should install tblib:

    pip install tblib

(...)

    subsuite_index, events = test_results.next(timeout=0.1)
  File "/usr/lib/python2.7/multiprocessing/pool.py", line 659, in next
    raise value
TypeError: can't pickle traceback objects

After installing tblib everything is ok:

(...)

----------------------------------------------------------------------
Ran 121 tests in 53.847s

FAILED (errors=2, skipped=2)