Replace hardcoded python version with ARG variable The Dockerfile had a hardcoded Python version in install paths and COPY command in the second stage build. Replace that with a hardcoded ARG pythonversion. Add RUN command to verify pythonversion against the actual version installed in the docker image. If they do not match generate an appropriate --build-arg for the docker build command that will match the docker image version. Document the use of the variable and why it's needed in installation.txt. Also fix typos referencing --build-args and bad values for the arguments.

[Unit]
Description=Roundup Server - roundup

[Service]
User=roundup
WorkingDirectory=/path/to/roundup/trackers/roundup
SyslogIdentifier=roundup-server-roundup
ExecStart=/path/to/gunicorn -b unix:///var/run/roundup/roundup.sock wsgi -w 4 --preload --max-requests 128 --max-requests-jitter 32 --timeout 60 --graceful-timeout 60 --access-logfile - --error-logfile
ExecReload=/bin/kill -HUP $MAINPID
ExecStop = /bin/kill -s TERM $MAINPID
KillMode=mixed
Restart=on-failure
RestartSec=15s

[Install]
WantedBy=multi-user.target