title: CommandError: /code/manage.py already exists, overlaying a project or app into an existing directory won't replace conflicting files
body: <p>I'm trying to run linux docker on windows and getting this error. </p>
  
  <p>build was fine. </p>
  
  <pre><code>'''
  $ docker-compose build
  Building web
  Step 1/11 : FROM python:3
   ---&gt; 42d620af35be
  Step 2/11 : ENV PYTHONUNBUFFERED 1
   ---&gt; Using cache
   ---&gt; b43065732d6e
  Step 3/11 : RUN apt-get update -y
   ---&gt; Using cache
   ---&gt; 6f65e0da9e14
  Step 4/11 : RUN apt-get install -y unixodbc unixodbc-dev
   ---&gt; Using cache
   ---&gt; 2a9d7445a991
  Step 5/11 : RUN easy_install pip
   ---&gt; Using cache
   ---&gt; 5994e6452e09
  Step 6/11 : RUN mkdir /code
   ---&gt; Using cache
   ---&gt; d0eaa870fb98
  Step 7/11 : WORKDIR /code
   ---&gt; Using cache
   ---&gt; af78d4b35f26
  Step 8/11 : RUN pip uninstall django
   ---&gt; Using cache
   ---&gt; 92f983bfef88
  Step 9/11 : COPY requirements.txt /code/
   ---&gt; Using cache
   ---&gt; 3c0031987286
  Step 10/11 : RUN pip install -r requirements.txt
   ---&gt; Using cache
   ---&gt; 3915127d3d58
  Step 11/11 : COPY . /code/
   ---&gt; Using cache
   ---&gt; de872685c733
  Successfully built de872685c733
  Successfully tagged djangoproject_web:latest
  '''
  </code></pre>
  
  <p>but when i run compose up.. i see below error.</p>
  
  <pre><code>'''
  $ docker-compose up
  Creating djangoproject_web_1 ... done
  Attaching to djangoproject_web_1
  web_1  | Watching for file changes with StatReloader
  web_1  | Performing system checks...
  web_1  |
  web_1  | System check identified no issues (0 silenced).
  web_1  |
  web_1  | You have 17 unapplied migration(s). Your project may not work properly until you apply the migrations for app(s): admin, auth, contenttypes, sessions.
  web_1  | Run 'python manage.py migrate' to apply them.
  web_1  | July 23, 2019 - 03:21:21
  web_1  | Django version 2.2.3, using settings 'composeexample.settings'
  web_1  | Starting development server at http://case.xxxxxx.com:8000/
  web_1  | Quit the server with CONTROL-C.
  web_1  | Error: [Errno -2] Name or service not known
  djangoproject_web_1 exited with code 1
  '''
  </code></pre>
  
  <p>and if i try this</p>
  
  <pre><code>'''
  docker-compose run web django-admin startproject composeexample .
  '''
  </code></pre>
  
  <p>it says</p>
  
  <pre><code>'''
  CommandError: /code/manage.py already exists, overlaying a project or app into an existing directory won't replace conflicting files
  '''
  </code></pre>
  
  <p>my Dockerfile is</p>
  
  <pre><code>'''
  FROM python:3
  ENV PYTHONUNBUFFERED 1
  RUN apt-get update -y
  RUN apt-get install -y unixodbc unixodbc-dev
  RUN easy_install pip
  RUN mkdir /code
  WORKDIR /code
  RUN pip uninstall django
  COPY requirements.txt /code/
  RUN pip install -r requirements.txt 
  COPY . /code/
  '''
  </code></pre>
  
  <p>my docker-compose.yml is
  '''
      version: '3'</p>
  
  <pre><code>services:
    web:
      build: .
      command: python manage.py runserver case.xxxxxx.com:8000
      volumes:
        - .:/code
      ports:
        - "8000:8000"
  </code></pre>
  
  <p>'''
  How can i fix the problem with composeexample? it is not even created (cause i can't see it in the folder).. your advice please. </p>