Just to note, I disagree entirely. Even in commercial development, it's the core premise of agile development to ship features early and continuously integrate feedback. Granted, lots of companies claim to do agile without actually doing it, but it's at least not a law of nature what you're describing.

But with this not being commercial development either way, I really don't feel like you can make any predictions. If the volunteer that implemented this sees your bug report, they could decide to drop everything else and fix that, because they get to pick their own priorities. They might have the solution in their head right away and it doesn't take them long at all to implement. Or someone new to the project might decide this sounds like a good issue to get started with.