An invalid ssl_certfile causes MongoClient to raise ssl.SSLError in Python2.7+

Python 2.7.10 (default, Oct 23 2015, 19:19:21)

[GCC 4.2.1 Compatible Apple LLVM 7.0.0 (clang-700.0.59.5)] on darwin

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>>> from pymongo.mongo_client import MongoClient

>>> import ssl

>>> MongoClient('localhost', ssl=True, ssl_cert_reqs=ssl.CERT_NONE,ssl_certfile='README.rst',serverSelectionTimeoutMS=100)

Traceback (most recent call last):

  File "<stdin>", line 1, in <module>

  File "pymongo/mongo_client.py", line 373, in __init__

    username, password, dbase, opts)

  File "pymongo/client_options.py", line 141, in __init__

    self.__pool_options = _parse_pool_options(options)

  File "pymongo/client_options.py", line 114, in _parse_pool_options

    ssl_context, ssl_match_hostname = _parse_ssl_options(options)

  File "pymongo/client_options.py", line 95, in _parse_ssl_options

    certfile, keyfile, passphrase, ca_certs, cert_reqs, crlfile)

  File "pymongo/ssl_support.py", line 116, in get_ssl_context

    ctx.load_cert_chain(certfile, keyfile)

ssl.SSLError: [SSL] PEM lib (_ssl.c:2580)