str object has no attribute decode

python3.6-setup.log

Sending build context to Docker daemon 203.8 kB
Step 1/4 : FROM python:3.6
 ---> 775dae9b960e
Step 2/4 : WORKDIR /tmp/app
 ---> 0a50baeafe90
Removing intermediate container 06d9206a8888
Step 3/4 : COPY requirements.txt requirements.txt
 ---> b8ee42a4b0f8
Removing intermediate container 3ef5cc0e069a
Step 4/4 : RUN python -m venv /tmp/venv &&     . /tmp/venv/bin/activate &&     pip install -r requirements.txt
 ---> Running in 2d54ddd8c53e
Collecting html==1.16 (from -r requirements.txt (line 4))
  Downloading html-1.16.tar.gz
    Complete output from command python setup.py egg_info:
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/tmp/pip-build-envcr513/html/setup.py", line 12, in <module>
        long_description = __doc__.decode('utf8'),
    AttributeError: 'str' object has no attribute 'decode'
    
    ----------------------------------------