Fixed bug where the error message for SQLite invalid isolation level on the
pysqlite driver would fail to indicate that "AUTOCOMMIT" is one of the
valid isolation levels.

Change-Id: Icbceab9a28af6a560859761fa92320b5473269a9
References: #6959

Also replace http://pypi.python.org/pypi with https://pypi.org/project

Change-Id: I84b5005c39969a82140706472989f2a30b0c7685

The fix for pysqlcipher released in version 1.4.3 :ticket:`5848` was
unfortunately non-working, in that the new ``on_connect_url`` hook was
erroneously not receiving a ``URL`` object under normal usage of
:func:`_sa.create_engine` and instead received a string that was unhandled;
the test suite failed to fully set up the actual conditions under which
this hook is called. This has been fixed.

Fixes: #6586
Change-Id: I3bf738daec35877a10fdad740f08dca9e7420829

The :class:`.TypeDecorator` class will now emit a warning when used in SQL
compilation with caching unless the ``.cache_ok`` flag is set to ``True``
or ``False``. ``.cache_ok`` indicates that all the parameters passed to the
object are safe to be used as a cache key, ``False`` means they are not.

Fixes: #6436
Change-Id: Ib1bb7dc4b124e38521d615c2e2e691e4915594fb

database created using filename uri

Default to using ``SingletonThreadPool`` for in-memory SQLite databases
created using URI filenames. Previously the default pool used was the
``NullPool`` that precented sharing the same database between multiple
engines.

Fixes: #6379
Closes: #6380
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/6380
Pull-request-sha: 3b8024417a3a54c8269d43e40801aa4e58593540

Change-Id: Ice09622796455e796ede7711c98f3ceec13aa949

The ``pysqlcipher`` dialect now imports the ``sqlcipher3`` module
for Python 3 by default.    Regressions have been repaired such that
the connection routine was not working.

To better support the post-connection steps of the pysqlcipher
dialect, a new hook Dialect.on_connect_url() is added, which
supersedes Dialect.on_connect() and is passed the URL object.
The dialect now pulls the passphrase and other cipher args
from the URL directly without including them in the
"connect" args.  This will allow any user-defined extensibility
to connecting to work as it would for other dialects.

The commit also builds upon the extended routines in
sqlite/provisioning.py to better support running tests against
multiple simultaneous SQLite database files.  Additionally enables
backend for test_sqlite which was skipping everything
for aiosqlite too, fortunately everything there is passing.

Fixes: #5848
Change-Id: I43f53ebc62298a84a4abe149e1eb699a027b7915

Added support for the aiosqlite database driver for use with the
SQLAlchemy asyncio extension.

Fixes: #5920
Change-Id: Id11a320516a44e886a6f518d2866a0f992413e55

Fixes: #5939
Change-Id: I21d7125765028e2a98d5ef4c32d8e7e457aa2d12

Change-Id: I9e425d2415d18a893342244755c7748b546fb20d

This introduces the ``_exclusive_against()`` utility decorator
that can be used to prevent repeated invocations of methods that
typically should only be called once.

An informative error message is now raised for a selected set of DML
methods (currently all part of :class:`_dml.Insert` constructs) if they are
called a second time, which would implicitly cancel out the previous
setting.  The methods altered include:
:class:`_sqlite.Insert.on_conflict_do_update`,
:class:`_sqlite.Insert.on_conflict_do_nothing` (SQLite),
:class:`_postgresql.Insert.on_conflict_do_update`,
:class:`_postgresql.Insert.on_conflict_do_nothing` (PostgreSQL),
:class:`_mysql.Insert.on_duplicate_key_update` (MySQL)

Fixes: #5169
Change-Id: I9278fa87cd3470dcf296ff96bb0fb17a3236d49d