[Release] DataStax Python Driver Version 3.9.0

[Jim Witschey]

We've released version 3.9.0 of the DataStax Python driver for Apache Cassandra.

This release focuses primarily on bugfixes. You can find the changelog
for this release reproduced below, or linked here:

https://github.com/datastax/python-driver/blob/master/CHANGELOG.rst#390

Many thanks to all who contributed code, wrote documentation, made
feature requests, reported bugs, and educated fellow community
members. We encourage you to stay involved:

- Discuss the driver and ask questions:
- Mailing List:
https://groups.google.com/a/lists.datastax.com/forum/#!forum/python-driver-user
- IRC: #datastax-drivers on irc.freenode.net
- Review and contribute source code and documentation:
https://github.com/datastax/python-driver/
- Report issues on JIRA: https://datastax-oss.atlassian.net/browse/PYTHON

Best,

Jim Witschey

3.9.0
=====

Features
--------
* cqlengine: remove elements by key from a map (PYTHON-688)

Bug Fixes
---------
* improve error handling when connecting to non-existent keyspace (PYTHON-665)
* Sockets associated with sessions not getting cleaned up on
session.shutdown() (PYTHON-673)
* rare flake on
integration.standard.test_cluster.ClusterTests.test_clone_shared_lbp
(PYTHON-727)
* MontonicTimestampGenerator.__init__ ignores class defaults (PYTHON-728)
* race where callback or errback for request may not be called (PYTHON-733)
* cqlengine: model.update() should not update columns with a default
value that hasn't changed (PYTHON-657)
* cqlengine: field value manager's explicit flag is True when queried
back from cassandra (PYTHON-719)

Other
-----
* Connection not closed in example_mapper (PYTHON-723)
* Remove mention of pre-2.0 C* versions from OSS 3.0+ docs (PYTHON-710)