httpbin: 0.6.2: self test failure: `static/` missing

When running the self tests for the pypi distfile of 0.6.2 on NetBSD 8.99.7/amd64 with python-3.6.3, I see the following test failure:

httpbin (unittest.loader._FailedTest) ... ERROR

======================================================================
ERROR: httpbin (unittest.loader._FailedTest)
----------------------------------------------------------------------
ImportError: Failed to import test module: httpbin
Traceback (most recent call last):
  File "/usr/pkg/lib/python3.6/unittest/loader.py", line 462, in _find_test_path
    package = self._get_module_from_name(name)
  File "/usr/pkg/lib/python3.6/unittest/loader.py", line 369, in _get_module_from_name
    __import__(name)
  File "/scratch/www/py-httpbin/work/httpbin-0.6.2/httpbin/__init__.py", line 3, in <module>
    from .core import *
  File "/scratch/www/py-httpbin/work/httpbin-0.6.2/httpbin/core.py", line 61, in <module>
    common = Common(app)
  File "/usr/pkg/lib/python3.6/site-packages/flask_common.py", line 95, in __init__
    self.init_app(app)
  File "/usr/pkg/lib/python3.6/site-packages/flask_common.py", line 112, in init_app
    app.wsgi_app = WhiteNoise(app.wsgi_app, root=url_for('static', filename='')[1:])
  File "/usr/pkg/lib/python3.6/site-packages/whitenoise/base.py", line 61, in __init__
    self.add_files(root, prefix)
  File "/usr/pkg/lib/python3.6/site-packages/whitenoise/base.py", line 96, in add_files
    self.update_files_dictionary(root, prefix)
  File "/usr/pkg/lib/python3.6/site-packages/whitenoise/base.py", line 101, in update_files_dictionary
    stat_cache = dict(scantree(root))
  File "/usr/pkg/lib/python3.6/site-packages/whitenoise/scantree.py", line 21, in scantree
    for entry in scandir(root):
FileNotFoundError: [Errno 2] No such file or directory: 'static/'