Description of the issue

The --env-file option added in PR #6535 doesn't appear to work. The commands accept the argument, but the variables from the specified env file don't make it into the environment.

I tried the option with run and up, both before and after the subcommand. For up it just gets ignored in either position. When I put it after run I get the usage message, but if I add the option into the options list in the run docstring, it accepts the option but ignores it, just like when it's in the other position.

Context information (for bug reports)

Output of docker-compose version

docker-compose version 1.25.0-rc1, build 8552e8e

Output of docker version

Docker version 18.09.5, build e8ff056

Steps to reproduce the issue

This makes a super-simple compose environment using the busybox image, creates default and override .env files, and runs the container to show the bug.

cat <<\EOF > docker-compose.yml
version: '3.7'
services:
  test:
    image: busybox
    env_file: .env.conf
EOF

echo 'WHEREAMI=config' > .env.conf
echo 'WHEREAMI=override' > .env.override

docker-compose --env-file .env.override run --rm test env | grep WHEREAMI

Observed result

WHEREAMI=config

Expected result

WHEREAMI=override

Additional information

If you remove the env_file line from the docker-compose.yml the variable disappears, so it's not a matter of preferring the config, it's just not managing to get the file from --env-file loaded into the environment.

Installation details: Ubuntu 18.04, using system Docker and installing docker-compose with pipenv, both as docker-compose==1.25.0-rc1 and by installing the cloned repo at master (same result).