There are many factors to consider in this specific case, and the fact that the source is a Maya file (an extra export involved) with pre-rotations on the animated joints, which something Unity does not support which forces a resample at FBX import in order to preserve existing animation properly. This means many different Maya, Maya FBX Exporters/options & Unity versions can be involved to track down the exact regression in a version that is not longer officially supported (more than 2 versions back). This combined with the fact that there are a couple possible workarounds, such as adding 1 extra key as padding before after the start/end times in Maya, (or not using pre-rotations on animated joints), are a very acceptable solutions. Fixing this issue would have a high risk of the result being different/wrong in other cases.
For all these reasons, we have no plans to address this issue in the near future.