Log Message:
py-celery: updated to 4.2.0

4.2.0:
- **Task**: Add ignore_result as task execution option
- **Redis Result Backend**: Do not create PubSub subscriptions when results are \ 
ignored
- **Redis Result Backend**: Result consumer always unsubscribes when task state \ 
is ready
- **Development/Testing**: Add docker-compose and base Dockerfile for development
- **Documentation/Sphinx**: Teach autodoc to document tasks if undoc-members is \ 
not set
- **Documentation/Sphinx**: Put back undoc-members option in sphinx test
- **Documentation/Sphinx**: Sphinx autodoc picks up tasks automatically only if \ 
undoc-members is set
- **Task**: Fix shadow_name issue when using previous version Task class
- **Task**: Add support for bound tasks as link_error parameter
- **Deployment**: Add a command line option for setting the Result Backend URL
- **CI**: Enable pip cache in appveyor build
- **Concurrency/Asynpool**: Fix errno property name shadowing.
- **DynamoDB Backend**: Configurable endpoint URL
- **Timezones**: Correctly detect UTC timezone and timezone from settings
- **Control**: Cleanup the mailbox's producer pool after forking
- **Documentation**: Start Celery and Celery Beat on Azure WebJob
- **Celery Beat**: Schedule due tasks on startup, after Beat restart has occurred
- **Worker**: Use absolute time when task is accepted by worker pool
- **Canvas**: Propagate arguments to chains inside groups
- **Canvas**: Fix Task.replace behavior in nested chords
- **Installation**: Pass python_requires argument to setuptools
- **Message Protocol Compatibility**: Handle "hybrid" messages that \ 
have moved between Celery versions
- **Canvas**: request on_timeout now ignores soft time limit exception
- **Redis Result Backend**: Integration test to verify PubSub unsubscriptions
- **Message Protocol Properties**: Allow the shadow keyword argument and the \ 
shadow_name method to set shadow properly
- **Canvas**: Run chord_unlock on same queue as chord body
- **Canvas**: Support chords with empty header group
- **Timezones**: make astimezone call in localize more safe
- **Canvas**: Fix length-1 and nested chords
- **CI**: Run Openstack Bandit <https://pypi.org/project/bandit/1.0.1/>_ \ 
in Travis CI in order to detect security issues.
- **CI**: Run isort <https://github.com/timothycrosley/isort>_ in Travis \ 
CI in order to lint Python **import** statements.
- **Canvas**: Resolve TypeError on .get from nested groups
- **CouchDB Backend**: Correct CouchDB key string type for Python 2/3 compatibility
- **Group Result**: Fix current_app fallback in GroupResult.restore()
- **Consul Backend**: Correct key string type for Python 2/3 compatibility
- **Group Result**: Correctly restore an empty GroupResult
- **Result**: Disable synchronous waiting for sub-tasks on eager mode
- **Celery Beat**: Detect timezone or Daylight Saving Time changes
- **Canvas**: Fix append to an empty chain.
- **Task**: Allow shadow to override task name in trace and logging messages.
- **Documentation/Sphinx**: Fix getfullargspec Python 2.x compatibility in \ 
contrib/sphinx.py
- **Documentation**: Updated installation instructions for SQS broker
- **Celery Beat**: Better equality comparison for ScheduleEntry instances
- **Task**: Adding 'shadow' property to as_task_v2
- Try to import directly, do not use deprecated imp method
- **Task**: Enable kwargsrepr and argsrepr override for modifying task argument \ 
representation
- **Result Backend**: Add Redis Sentinel backend
- Use unique time values for Collections/LimitedSet
- **CI**: Report coverage for all result backends.
- **Django**: Use Django DB max age connection setting
- **Canvas**: Properly take into account chain tasks link_error
- **Canvas**: Allow to create group with single task
- **Canvas**: Copy dictionary parameter in chord.from_dict before modifying
- **Results Backend**: Add Cassandra options
- **Worker**: Apply rate limiting for tasks with ETA
- **Celery Beat**: support scheduler entries without a schedule
- **SQS Broker**: Updated SQS requirements file with correct boto3 version
- Remove unused code from _create_app contextmanager
- **Group Result**: Modify GroupResult.as_tuple() to include parent
- **Beat**: Set default scheduler class in beat command.
- **Worker**: Retry signal receiver after raised exception
- **Task**: Allow custom Request class for tasks
- **Django**: Django fixup should close all cache backends
- **Deployment**: Adds stopasgroup to the supervisor scripts
- Using Exception.args to serialize/deserialize exceptions
- **Timezones**: Correct calculation of application current time with timezone
- **Remote Debugger**: Set the SO_REUSEADDR option on the socket
- **Django**: Celery ignores exceptions raised during django.setup()
- Use heartbeat setting from application configuration for Broker connection
- **Celery Beat**: Fixed exception caused by next_transit receiving an \ 
unexpected argument.
- **Task** Introduce exponential backoff with Task auto-retry
- **AsyncResult**: Remove weak-references to bound methods in AsyncResult promises.
- **Development/Testing**: Allow eager application of canvas structures
- **Command Line**: Flush stderr before exiting with error code 1.
- **Task**: Escapes single quotes in kwargsrepr strings.
- **AsyncResult**: Restore ability to join over ResultSet after fixing celery/3818.
- **Redis Results Backend**: Unsubscribe on message success.
  Previously Celery would leak channels, filling the memory of the Redis instance.
- **Task**: Only convert eta to isoformat when it is not already a string.
- **Redis Results Backend**: The result_backend setting now supports rediss:// URIs
- **Canvas** Keyword arguments are passed to tasks in chain as expected.
- **Django** Fix a regression casuing Celery to crash when using Django.
- **Canvas** Chain with one task now runs as expected.
- **Kombu** Celery 4.2 now requires Kombu 4.2 or better.
- GreenletExit is not in __all__ in greenlet.py which can not be imported by \ 
Python 3.6.
  The import was adjusted to work on Python 3.6 as well.
- Fixed a regression that occured during the development of Celery 4.2 which \ 
caused celery report to crash when Django is installed.
- Matched the behavior of GroupResult.as_tuple() to that of AsyncResult.as_tuple().
  The group's parent is now serialized correctly.
- Use Redis coercion mechanism for converting URI query parameters.
- Fixed the representation of GroupResult.