old_contents: from __future__ import with_statement
  from alembic import context
  from sqlalchemy import engine_from_config, pool
  from logging.config import fileConfig
  import os
  import pymysql
  
  # this is the Alembic Config object, which provides
  # access to the values within the .ini file in use.
  config = context.config
  
  # Interpret the config file for Python logging.
  # This line sets up loggers basically.
  fileConfig(config.config_file_name)
  
  # add your model's MetaData object here
  # for 'autogenerate' support
  # from myapp import mymodel
  # target_metadata = mymodel.Base.metadata
  target_metadata = None
  
  # other values from the config, defined by the needs of env.py,
  # can be acquired:
  # my_important_option = config.get_main_option("my_important_option")
  # ... etc.
  
  
  def run_migrations_offline():
      """Run migrations in 'offline' mode.
  
      This configures the context with just a URL
      and not an Engine, though an Engine is acceptable
      here as well.  By skipping the Engine creation
      we don't even need a DBAPI to be available.
  
      Calls to context.execute() here emit the given string to the
      script output.
  
      """
      url = config.get_main_option("sqlalchemy.url")
      context.configure(
          url=url, target_metadata=target_metadata, literal_binds=True)
  
      with context.begin_transaction():
          context.run_migrations()
  
  
  def run_migrations_online():
      """Run migrations in 'online' mode.
  
      In this scenario we need to create an Engine
      and associate a connection with the context.
  
      """
      for name in ["CLEARDB_DATABASE_URL", "SQLALCHEMY_DATABASE_URI"]:
          if os.environ.get(name):
              if name.startswith("mysql://"):
                  config.set_main_option(
                      "sqlalchemy.url",
                      os.environ.get(name.replace("mysql://", "mysql+pymysql://")))
              else:
                  config.set_main_option("sqlalchemy.url", os.environ.get(name))
  
      connectable = engine_from_config(
          config.get_section(config.config_ini_section),
          prefix='sqlalchemy.',
          poolclass=pool.NullPool)
  
      with connectable.connect() as connection:
          context.configure(
              connection=connection,
              target_metadata=target_metadata
          )
  
          with context.begin_transaction():
              context.run_migrations()
  
  if context.is_offline_mode():
      run_migrations_offline()
  else:
      run_migrations_online()
  
new_contents: from __future__ import with_statement
  from alembic import context
  from sqlalchemy import engine_from_config, pool
  from logging.config import fileConfig
  import os
  import pymysql
  
  # this is the Alembic Config object, which provides
  # access to the values within the .ini file in use.
  config = context.config
  
  # Interpret the config file for Python logging.
  # This line sets up loggers basically.
  fileConfig(config.config_file_name)
  
  # add your model's MetaData object here
  # for 'autogenerate' support
  # from myapp import mymodel
  # target_metadata = mymodel.Base.metadata
  target_metadata = None
  
  # other values from the config, defined by the needs of env.py,
  # can be acquired:
  # my_important_option = config.get_main_option("my_important_option")
  # ... etc.
  
  
  def run_migrations_offline():
      """Run migrations in 'offline' mode.
  
      This configures the context with just a URL
      and not an Engine, though an Engine is acceptable
      here as well.  By skipping the Engine creation
      we don't even need a DBAPI to be available.
  
      Calls to context.execute() here emit the given string to the
      script output.
  
      """
      url = config.get_main_option("sqlalchemy.url")
      context.configure(
          url=url, target_metadata=target_metadata, literal_binds=True)
  
      with context.begin_transaction():
          context.run_migrations()
  
  
  def run_migrations_online():
      """Run migrations in 'online' mode.
  
      In this scenario we need to create an Engine
      and associate a connection with the context.
  
      """
      database_url = os.environ.get("CLEARDB_DATABASE_URL")
      if database_url and database_url.startswith("mysql://"):
          database_url = database_url.replace("mysql://", "mysql+pymysql://")
          database_url = database_url.replace("?reconnect=true", "")
          config.set_main_option("sqlalchemy.url", database_url)
      else:
          config.set_main_option("sqlalchemy.url", database_url)
  
      connectable = engine_from_config(
          config.get_section(config.config_ini_section),
          prefix='sqlalchemy.',
          poolclass=pool.NullPool)
  
      with connectable.connect() as connection:
          context.configure(
              connection=connection,
              target_metadata=target_metadata
          )
  
          with context.begin_transaction():
              context.run_migrations()
  
  if context.is_offline_mode():
      run_migrations_offline()
  else:
      run_migrations_online()
  
subject: Fix migration error for initial CLEARDB_DATABASE_URL