That is only true for projects where you need to deploy. In that case, yeah, you of course can only close the bug once you fixed production. But for normal software development, you can fix the bug in the software and you can update the bug tracker, and then push everything once you're back online.
For example, on a flight, I can look at the bug tracker (since it's part of the clone), pick a bug I want to work on, create a few commits to fix it, then update that bug (set it to closed, reference the commits that fixed it), and then upload it all when the plane landed again.
For example, on a flight, I can look at the bug tracker (since it's part of the clone), pick a bug I want to work on, create a few commits to fix it, then update that bug (set it to closed, reference the commits that fixed it), and then upload it all when the plane landed again.