Tempo beating at the whole does not export in .musicxml format

Hello everyone,

I've noticed a tiny bug when MuseScore exports in .musicxml format. When the tempo is set at the quarter or at the half note, the corresponding tag indicates:

«beat-unit»quarter«/beat-unit»
«per-minute»90«/per-minute»

or

«beat-unit»half«/beat-unit»
«per-minute»90«/per-minute»

But when the tempo is set at the whole, it lets the beat-unit field empty, which may cause some problems depending on the software you use to read it:

«beat-unit»«/beat-unit»
«per-minute»90«/per-minute»

I correct those manually with a text editor, but maybe that would be worth it to fix it—although I recognize this is not an urgent matter.

Best,
Silvain