Getting error while installing ruamel-yaml-clib I am using CKAN 2.8.6 version

[wishtree-hmanglani]

CKAN version
2.8.6
Describe the bug
Till now it's working fine but suddenly I am getting error while pip install pymssql==2.1.4 version. This library initially install ruamel.yaml.clib>=0.1.2. That throw the error as bellow:

#11 80.05 Downloading ruamel.yaml.clib-0.2.4.tar.gz (180 kB)
#11 80.17 ERROR: Command errored out with exit status 1:
#11 80.17 command: /usr/bin/python -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-install-0ba0Bm/ruamel-yaml-clib/setup.py'"'"'; file='"'"'/tmp/pip-install-0ba0Bm/ruamel-yaml-clib/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(file);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, file, '"'"'exec'"'"'))' egg_info --egg-base /tmp/pip-pip-egg-info-54UfpG
#11 80.17 cwd: /tmp/pip-install-0ba0Bm/ruamel-yaml-clib/
#11 80.17 Complete output (1 lines):
#11 80.17 minimum python version(s): [(3, 5)]
#11 80.17 ----------------------------------------
#11 80.17 ERROR: Command errored out with exit status 1: python setup.py egg_info Check the logs for full command output.

That basically throws an error that required python 3 but as we know ckan-2.8.* not support python3
Steps to reproduce
Steps to reproduce the behavior:
I am using docker-compose up that RUN command: pip install -r requirement.txt

requirement.txt
pymssql==2.1.4
requirment.txt
functools32==3.2.3.post2
tensorflow==1.6.0
keras==2.2.4
h5py==2.9.0
filelock==3.0.12
spacy==2.2.3
goodtables==1.5.1
hdx-python-api==4.3.0
humanize==1.0.0
pycountry==19.8.18
pyrsistent == 0.16.0

Expected behavior
This should be installed in CKAN 2.8.6

Expected behavior
Install ruamel-yaml-clib successfully.

Additional details