title: `flask db migrate` error
body: <p>We are trying to run a <code>flask db migrate</code> and <code>flask db upgrade</code> which throws the following error:</p>
  
  <blockquote>
  <pre><code>Usage: flask db upgrade [OPTIONS] [REVISION]
  
  Error: The file/path provided (C) does not appear to exist.  Please verify the path 
             is correct.  If app is not on PYTHONPATH, ensure the extension is .py
  </code></pre>
  </blockquote>
  
  <p>We have added the app's directory to the <code>PYTHONPATH</code> environment variable but still get the error. Any help would be appreciated.</p>
  
  <p>Below is our <code>__init__.py</code> code. Are we missing something?</p>
  
  <pre><code>import logging
  from flask import Flask
  from flask_appbuilder import SQLA, AppBuilder
  
  """
   Logging configuration
  """
  
  logging.basicConfig(format='%(asctime)s:%(levelname)s:%(name)s:%(message)s')
  logging.getLogger().setLevel(logging.DEBUG)
  
  app = Flask(__name__)
  app.config.from_object('config')
  db = SQLA(app)
  appbuilder = AppBuilder(app, db.session)
  migrate.init_app(app, db)
  
  
  """
  from sqlalchemy.engine import Engine
  from sqlalchemy import event
  
  #Only include this for SQLLite constraints
  @event.listens_for(Engine, "connect")
  def set_sqlite_pragma(dbapi_connection, connection_record):
      # Will force sqllite contraint foreign keys
      cursor = dbapi_connection.cursor()
      cursor.execute("PRAGMA foreign_keys=ON")
      cursor.close()
  """    
  
  from app import views
  </code></pre>