Rapid Board Burndown Chart and Sprint Report show older story point field value

If an issue has several changes to its story points field before starting a sprint, the chart and report are supposed to show the last changed-to value. Due to this bug this is not always the case.

Example:
SP field changed from 3 -> 6, then 6 -> 8, then 8 -> 3, then the Sprint is started. Naturally 3 SP should show up on both, the burndown and the report. Currently this isn't always the case, so 6 or 8 or even no value could be shown.

This bug applies to statistic value burndowns, but not to the hour burndown chart.