I propose that bugs meeting that description (such as #4398) simply be marked as having status "Fixed". The "Fixed in Master" status seems misleading: They are not going to get fixed in stable. If we mark them Fixed, it can mean: We are done with them.
Note that this is different from having the *resolution* be fixed: These would still have no resolution and so would still turn up the right way in searches. The only difference would be that "fixedinmaster" would mean: Fixed in master and (possibly, probably) to be fixed in stable. Richard