Agile burndown chart shows closed issues as having remaining time

The agile burndown chart uses the issue's Remaining hours field even if the issue is closed. This makes little sense--if the issue is closed, then by definition it has 0 remaining time.

This is a big annoyance: the chart becomes wildly inaccurate if we consistently use less time than estimated to satisfy issues.

Because of this, I have to either log work myself (as the admin) or force my devs to mark remaining time as 0. This usually means a separate use of the Log work dialog, which requires us to log work every time we adjust the issue's remaining time. This makes a mess of time reporting and is a pointless step since, again, a closed issue has no remaining work. Otherwise, it shouldn't be closed.

Further, what if we need to reopen the issue? It would be nice to keep burning against its remaining time instead of having to totally re-estimate because we had to manually force it to 0 time before closing it.

Expected behavior: If I close an issue, the agile burndown chart should consider the issue as having 0 remaining time regardless of the value of its Remaining hours field.