Alas, you and I simply disagree. I wager that full responsibility for ones project implies the onus of fixing whatever problems you introduce into the project

Alas, you and I simply disagree. I wager that full responsibility for ones project implies the onus of fixing whatever problems you introduce into the project by importing the external dependency in the first place. Were you my junior, telling this to me as your project manager, I'd demand you fix the bug. The reason is - we already gained from your decision to advance the project by including the external work, and at the moment you included it in your project you accepted responsibility for the issue. Failing to take responsibility for this code, whether you wrote it or not, would be a major distraction from the task, and thus does not reflect positively on you as a developer...