'pip install' fails with "TypeError: 'encoding' is an invalid keyword argument for this function"

[130s]

With Py2 on Ubuntu 18.04 I get this.

$ docker pull ubuntu:bionic 
bionic: Pulling from library/ubuntu
Digest: sha256:0fedbd5bd9fb72089c7bbca476949e10593cebed9b1fb9edf5b79dbbacddd7d6
Status: Image is up to date for ubuntu:bionic
docker.io/library/ubuntu:bionic

$ docker run -it ubuntu:bionic bash

root@649f8291c2e8:/# apt update && apt install -y python-pip && pip install ruyaml
Collecting ruyaml
  Downloading https://files.pythonhosted.org/packages/a0/cf/6fd65b5fcca95ecde2f26f71709ee02ab305487327cc4b08522399179883/ruyaml-0.19.0.tar.gz (226kB)
    100% |################################| 235kB 2.8MB/s 
    Complete output from command python setup.py egg_info:
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/tmp/pip-build-TPl3zQ/ruyaml/setup.py", line 3, in <module>
        LONG_DESC = open("README.rst", encoding="utf-8").read()
    TypeError: 'encoding' is an invalid keyword argument for this function
    
    ----------------------------------------
Command "python setup.py egg_info" failed with error code 1 in /tmp/pip-build-TPl3zQ/ruyaml/

But Py3 seems to be ok on 18.04.

$ docker run -it ubuntu:bionic bash

# apt update && apt install -y python3-pip && pip3 install ruyaml

Processing triggers for ca-certificates (20210119~18.04.2) ...
Updating certificates in /etc/ssl/certs...
0 added, 0 removed; done.
Running hooks in /etc/ca-certificates/update.d...
done.
Collecting ruyaml
  Downloading https://files.pythonhosted.org/packages/7d/9a/ec93200953ae3e8687ad6ad962d7a3ad306fc81048e6ed3dcb350be7786c/ruyaml-0.20.0-py2.py3-none-any.whl (96kB)
    100% |################################| 102kB 2.4MB/s 
Collecting distro>=1.3.0 (from ruyaml)
  Downloading https://files.pythonhosted.org/packages/b3/8d/a0a5c389d76f90c766e956515d34c3408a1e18f60fbaa08221d1f6b87490/distro-1.6.0-py2.py3-none-any.whl
Requirement already satisfied: setuptools>=39.0 in /usr/lib/python3/dist-packages (from ruyaml)
Installing collected packages: distro, ruyaml
Successfully installed distro-1.6.0 ruyaml-0.20.0

Btw on Focal with Python3, this doesn't happen either.

root@d2484b1ee0a7:/# pip3 install ruyaml
Collecting ruyaml
  Downloading ruyaml-0.20.0-py2.py3-none-any.whl (96 kB)
     |████████████████████████████████| 96 kB 2.9 MB/s 
Collecting distro>=1.3.0
  Downloading distro-1.6.0-py2.py3-none-any.whl (19 kB)
Requirement already satisfied: setuptools>=39.0 in /usr/lib/python3/dist-packages (from ruyaml) (45.2.0)
Installing collected packages: distro, ruyaml
Successfully installed distro-1.6.0 ruyaml-0.20.0