merge 3.20.9 into 3.21
Fix conflict in unittest_postgres.py by changing sources configuration
in PostgresTimeoutConfiguration.__init__ so it happens *after*
setUpModule().
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Changelog history
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.. include:: 3.21.rst
.. include:: 3.20.rst
.. include:: 3.19.rst
.. include:: 3.18.rst
.. include:: 3.17.rst
.. include:: 3.16.rst
.. include:: 3.15.rst
.. include:: 3.14.rst