An @contextmanager will raise an exception from its yield statement if
an exception happens in the with-block that uses it. If the context
manager needs to do clean up, it should do it even if an exception is
raised, so it needs to be done in a finally clause.
A named outer is suitable when dealing with IntegrityErrors. It only
checks that it is not nested under an atomic only if it is nested
under enable_outer_atomic(name=<name>). This way only the view which
is causing IntegrityErrors needs to have its automatic transaction
management disabled and other callers are not effected.
By default, migrations are applied as they always have been. Exporting DISABLE_MIGRATIONS=1 or passing --disable-migrations to Paver commands will create tables directly from apps' models.
