Compose: Quoted volumes path interpreted as named volume

Foreword

Tested with 1.8.1 and 1.9.0-rc4

Not Working

volumes:
  - "$MYSQL_DIRECTORY:/var/lib/mysql"

and

volumes:
  - "${MYSQL_DIRECTORY}:/var/lib/mysql"

export MYSQL_DIRECTORY="/foo"
ERROR: compose.cli.main.main: Named volume ""/foo":/var/lib/mysql:rw" is used in service "mysql" but no declaration was found in the volumes section.`



md5-f8234cc07328abd5fb7fe33f36bbeef1



```bash
export MYSQL_DIRECTORY=/foo

Suggestion

docker-compose should treat quoted absolute paths as paths