Sourced from alembic's releases.

1.2.0

Released: September 20, 2019

• [command] [feature] Added new --purge flag to the alembic stamp command, which will
  unconditionally erase the version table before stamping anything. This is
  useful for development where non-existent version identifiers might be left
  within the table. Additionally, alembic.stamp now supports a list of
  revision identifiers, which are intended to allow setting up muliple heads
  at once. Overall handling of version identifiers within the
  alembic.stamp command has been improved with many new tests and
  use cases added.

  References: #473

• [autogenerate] [bug] Improved the Python rendering of a series of migration operations such that
  a single "pass" is rendered for a UpgradeOps or
  DowngradeOps based on if no lines of Python code actually
  rendered under the operation, rather than whether or not sub-directives
  exist. Removed extra "pass" lines that would generate from the
  ModifyTableOps directive so that these aren't duplicated under
  operation rewriting scenarios.

  References: #550

• [feature] [runtime] Added new feature MigrationContext.autocommit_block(), a special
  directive which will provide for a non-transactional block inside of a
  migration script. The feature requres that: the database driver
  (e.g. DBAPI) supports the AUTOCOMMIT isolation mode. The directive
  also necessarily needs to COMMIT the existing transaction in progress
  in order to enter autocommit mode.

  References: #123

• [change: py3k] Python 3.4 support is dropped, as the upstream tooling (pip, mysqlclient)
  etc are already dropping support for Python 3.4, which itself is no longer
  maintained.

• [autogenerate] [usecase] Added autogenerate support for Column objects that have
  dialect-specific **kwargs, support first added in SQLAlchemy 1.3.
  This includes SQLite "on conflict" as well as options used by some
  third party dialects.

  References: #518

• [autogenerate] [usecase] Added rendering for SQLAlchemy Variant datatypes, which render as the
  base type plus one or more .with_variant() method calls.

  References: #131

... (truncated)

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