zeep, infinite recursion

[Nagy László Zsolt]

> There are less than 100 elements defined in the WSDL, so it cannot be
> the problem. It might be a recursive data definition, but then it should
> be handled by zeep instead of entering into an intinite recursion.
>
> Well, I'll be working on an MWE and post it here later.
It was easier than I thought. It seems that zeep has a problem
processing a basic WS-Security STS (Security Token Service, plain
username+password authentication) document. I have changed the endpoint
URL to example.com. Total size 11K compressed. I hope it is okay to
attach here.

To reproduce the problem, just run this:

python3.6 -m zeep sts-username.wsdl

BTW, python version is 3.6.1, and here is a list of installed modules
with full version numbers:

appdirs (1.4.3)
asn1crypto (0.22.0)
cached-property (1.3.0)
certifi (2017.4.17)
cffi (1.10.0)
chardet (3.0.3)
cryptography (1.8.1)
defusedxml (0.5.0)
idna (2.5)
isodate (0.5.4)
lxml (3.7.3)
ndg-httpsclient (0.4.2)
packaging (16.8)
pip (9.0.1)
pkgconfig (1.2.2)
pyasn1 (0.2.3)
pycparser (2.17)
pycurl (7.43.0)
pygobject (3.20.0)
pyOpenSSL (17.0.0)
pyparsing (2.2.0)
python-apt (1.1.0b1)
pytz (2017.2)
requests (2.17.3)
requests-toolbelt (0.8.0)
setuptools (35.0.2)
six (1.10.0)
ssh-import-id (5.5)
tornado (4.5.1)
unattended-upgrades (0.1)
urllib3 (1.21.1)
wheel (0.29.0)
xmlsec (1.0.9)
zeep (2.0.0)