TypeError: If post_mortem is specified, full exc_info must be passed!

[Marius Gedminas]

If you have a test module that cannot be imported or has no tests *and* run zope-testrunner -D, you get this error:

Traceback (most recent call last):
  File "bin/test", line 20, in <module>
    '--test-path', '/home/mg/src/zope.testrunner/src',
  File "/home/mg/src/zope.testrunner/src/zope/testrunner/__init__.py", line 30, in run
    failed = run_internal(defaults, args, script_parts=script_parts)
  File "/home/mg/src/zope.testrunner/src/zope/testrunner/__init__.py", line 43, in run_internal
    runner.run()
  File "/home/mg/src/zope.testrunner/src/zope/testrunner/runner.py", line 136, in run
    feature.global_setup()
  File "/home/mg/src/zope.testrunner/src/zope/testrunner/find.py", line 477, in global_setup
    tests = find_tests(self.runner.options, self.runner.found_suites)
  File "/home/mg/src/zope.testrunner/src/zope/testrunner/find.py", line 163, in find_tests
    for suite in found_suites:
  File "/home/mg/src/zope.testrunner/src/zope/testrunner/find.py", line 198, in find_suites
    + (sys.exc_info()[2].tb_next.tb_next,),
  File "/home/mg/src/zope.testrunner/src/zope/testrunner/find.py", line 131, in __init__
    raise TypeError('If post_mortem is specified, '
TypeError: If post_mortem is specified, full exc_info must be passed!

To reproduce:
    check out zope.testrunner
    python bootstrap.py
    bin/buildout
    edit src/zope/testrunner/tests.py and introduce a syntax error
    bin/test -D

[Marius Gedminas (mgedmin)]

A related but different bug: instead of a syntax error (that would raise during import time) cause an invalid test_suite to be returned (e.g. return None) and try bin/test -D. Same error, different place.