Regular expression does not match correctly against statements that contain
comments at their start. So strip those comments first (and whitespaces, while
we are at it).

Change-Id: Iad9b544bf995374d76cab1e125658aae2f8511f4
Closes-Bug: #1410494

Now that we don't run SQL script with a single .execute() call,
transaction management statements (BEGIN, COMMIT, END) fail with
operational error. Ignore them if occurred in a script.

All in all, transactions are managed by SQLAlchemy-migrate itself, so
there is no reason for the calling code to pass those statements in a
SQL script. Warn user about the statements that are ignored.

The ideal response to such a warning from library users is removing
those redundant transaction management statements from their scripts.

Note: ROLLBACK is not ignored even though it's one of transaction
management statements because its usage in migration scripts is insane
anyway, and we're better fail on it and not (almost) silently ignore it.

Change-Id: Ie4179c0e9341d42656d66821aaac23f8dcd33927
Closes-bug: 1368391

Some drivers [f.e. MySQL Connector] do not like multiple statements
being passed to .execute(). They require either passing multi=True
parameter to .execute() that is not DB-API 2.0 defined, or executing
those statements one by one.

For that patch, I've chosen the second option to stay away from driver
specific hacks.

Also removed SQLite hack that seems to be related to the same multiple
statements issue.

blueprint enable-mysql-connector

Change-Id: Ic6d53ed1fef8aee9471f3540f06b39cd5ee4ef82

If SQL script failed, we don't currently log the failure anywhere, so
users have hard time debugging an issue, if anything arises.

Let's log the failure before proceeding with rollback.

Change-Id: Ic92b1403c00bb238a68265a15150a4be6f6b2346

Brief summary of the modifications:

* Use six for compatibility with both Python 2 and 3;
* Replace UserDict.DictMixin with collections.MutableMapping;
* Fix relative imports;
* Use test-requirements.txt for requirements that are common to both Python 2
  and 3, and test-requirements-py{2,3}.txt for version-specific requirements;
* Miscellaneous fixes.
* Use a specific test_db_py3.cfg file for Python 3, that only runs tests on
  sqlite.

Thanks to Victor Stinner who co-wrote this patch.

Change-Id: Ia6dc536c39d274924c21fd5bb619e8e5721e04c4
Co-Authored-By: Victor Stinner <victor.stinner@enovance.com>

Remove all trailing spaces and tabs in every file in the project.
People have editors configured to do this, which causes them to
accidentally make little whitespace changes in unrelated commits,
which makes those commits harder to review.  Better to fix them all
at once.

Change-Id: I17d89f55f41d8599e0ab1a31f646cd161289703e