#14910 fixed the regression introduced by #13873 where sqlite database
migrations would no longer run inside a transaction. However, it
committed the transaction before Synapse updated its bookkeeping of
which migrations have been run, which means that migrations may be run
again after they have completed successfully.

Leave the transaction open at the end of `executescript`, to restore the
old, correct behaviour. Also make the PostgreSQL behaviour consistent
with SQLite.

Fixes #14909.

Signed-off-by: Sean Quah <seanq@matrix.org>

Adds missing type hints to `tests.storage` package
and does not allow untyped definitions.

To handle cancellation, we ensure that `after_callback`s and
`exception_callback`s are always run, since the transaction will
complete on another thread regardless of cancellation.

We also wait until everything is done before releasing the
`CancelledError`, so that logging contexts won't get used after they
have been finished.

Signed-off-by: Sean Quah <seanq@element.io>

Signed-off-by: Sean Quah <seanq@element.io>

Signed-off-by: Sean Quah <seanq@element.io>

Part of #9744

Removes all redundant `# -*- coding: utf-8 -*-` lines from files, as python 3 automatically reads source code as utf-8 now.

`Signed-off-by: Jonathan de Jong <jonathan@automatia.nl&gt;`>

We seem to have some duplicates, which could do with being cleared out.