Replacing samples that are in use by a player unit could result in garbage being sent down the chain

[odevices]

Report is here: https://forum.orthogonaldevices.com/t/v0-6-x-release-candidate-packages-and-mods/5246/307?u=odevices

I haven't reproduced yet but I suspect that a race condition in Head::setSample is the culprit.