Pass connect_args={'check_same_thread': False} when creating the SQLite
engine in get_current_revision(), consistent with init_or_upgrade() which
already does this for all SQLite engines. Without this flag, calling
get_current_revision() from a thread other than the one that created the
engine raises a ProgrammingError.
Add a Behave scenario to verify the connect_args are passed correctly.
ISSUES CLOSED: #10952
HAL9000