Encapsulating retries into `with` block

Is it possible to repeat the code within a with statement?

No.

As pointed out earlier in that mailing list thread, you can reduce a bit of duplication by making the decorator call the passed function:

def do_work():
    ...
    # This is not ideal!
    @transaction(retries=3)
    def _perform_in_transaction():
        # Atomic DB statements
        ...
    # called implicitly
    ...