pipenv: RuntimeError: maximum recursion depth exceeded

Trying to convert my production app, I get a recursion error:

$ cat requirements.txt | wc -l
     201

$ pipenv lock   
Requirements.txt found, instead of Pipfile! Converting…
Traceback (most recent call last):
  File "/Users/philfreo/Library/Python/2.7/bin/pipenv", line 11, in <module>
    sys.exit(cli())
  File "/Users/philfreo/Library/Python/2.7/lib/python/site-packages/pipenv/vendor/click/core.py", line 722, in __call__
    return self.main(*args, **kwargs)
  File "/Users/philfreo/Library/Python/2.7/lib/python/site-packages/pipenv/vendor/click/core.py", line 697, in main
    rv = self.invoke(ctx)
  File "/Users/philfreo/Library/Python/2.7/lib/python/site-packages/pipenv/vendor/click/core.py", line 1066, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/Users/philfreo/Library/Python/2.7/lib/python/site-packages/pipenv/vendor/click/core.py", line 895, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/Users/philfreo/Library/Python/2.7/lib/python/site-packages/pipenv/vendor/click/core.py", line 535, in invoke
    return callback(*args, **kwargs)
  File "/Users/philfreo/Library/Python/2.7/lib/python/site-packages/pipenv/cli.py", line 1787, in lock
    ensure_project(three=three, python=python)
  File "/Users/philfreo/Library/Python/2.7/lib/python/site-packages/pipenv/cli.py", line 577, in ensure_project
    ensure_pipfile(validate=validate)
  File "/Users/philfreo/Library/Python/2.7/lib/python/site-packages/pipenv/cli.py", line 291, in ensure_pipfile
    import_requirements()
  File "/Users/philfreo/Library/Python/2.7/lib/python/site-packages/pipenv/cli.py", line 251, in import_requirements
    project.add_package_to_pipfile(str(package.req), dev=dev)
  File "/Users/philfreo/Library/Python/2.7/lib/python/site-packages/pipenv/project.py", line 413, in add_package_to_pipfile
    p = self._pipfile
  File "/Users/philfreo/Library/Python/2.7/lib/python/site-packages/pipenv/project.py", line 212, in _pipfile
    pfile = self.parsed_pipfile
  File "/Users/philfreo/Library/Python/2.7/lib/python/site-packages/pipenv/project.py", line 207, in parsed_pipfile
    return contoml.loads(contents)
  File "/Users/philfreo/Library/Python/2.7/lib/python/site-packages/pipenv/patched/contoml/__init__.py", line 15, in loads
    elements = parse_tokens(tokens)
  File "/Users/philfreo/Library/Python/2.7/lib/python/site-packages/pipenv/patched/prettytoml/parser/__init__.py", line 17, in parse_tokens
    return _parse_token_stream(TokenStream(tokens))
  File "/Users/philfreo/Library/Python/2.7/lib/python/site-packages/pipenv/patched/prettytoml/parser/__init__.py", line 29, in _parse_token_stream
    elements, pending = toml_file_elements(token_stream)
  File "/Users/philfreo/Library/Python/2.7/lib/python/site-packages/pipenv/patched/prettytoml/parser/parser.py", line 375, in toml_file_elements
    captured = capture_from(token_stream).find(one).or_find(file_entry_element).or_empty()
 
.......... middle of very large stack trace omitted (lmk if you want the full version) ......

    element, pending_ts = finder(self._token_stream)
  File "/Users/philfreo/Library/Python/2.7/lib/python/site-packages/pipenv/patched/prettytoml/parser/parser.py", line 98, in more
    c = capture_from(ts).find(token(token_type)).and_find(zero_or_more_tokens(token_type))
  File "/Users/philfreo/Library/Python/2.7/lib/python/site-packages/pipenv/patched/prettytoml/parser/recdesc.py", line 33, in find
    element, pending_ts = finder(self._token_stream)
  File "/Users/philfreo/Library/Python/2.7/lib/python/site-packages/pipenv/patched/prettytoml/parser/parser.py", line 58, in factory
    raise ParsingError('Expected a token of type {}'.format(token_type))
  File "/Users/philfreo/Library/Python/2.7/lib/python/site-packages/pipenv/patched/prettytoml/tokens/__init__.py", line 30, in __repr__
    return "{}-{}".format(self.priority, self._name)
RuntimeError: maximum recursion depth exceeded

It makes some good progress before crashing:

$ cat Pipfile | wc -l 
     193