Why is security/py-pywinrm limited to Python 2.7 only?

[Pavel Timofeev]

Hello.
I'm curious why security/py-pywinrm is limited to python 2.7 now.

I tried it with python 3.6:

--- security/py-pywinrm/Makefile.orig    2019-04-03 10:45:08.434229000 +0300
+++ security/py-pywinrm/Makefile    2019-04-03 10:45:13.713012000 +0300
@@ -19,7 +19,7 @@
         ${PYTHON_PKGNAMEPREFIX}requests-credssp>=0.0.1:security/py-requests-credssp@${PY_FLAVOR}

 NO_ARCH=    yes
-USES=        python:2.7
+USES=        python
 USE_PYTHON=    autoplist distutils

 .include <bsd.port.mk>


Port was successfully rebuilt (on FBSD12) with python3.6.
Some basic operation works at least with ntlm auth,

What is/was wrong with the port? I suppose it's worth to document it
if there is a problem.