Daniel Barkalow [off-list ref] writes:
... these are actually distinguishable, IIRC, by whether the
mode bits are set or not, but current code doesn't check that.
IIRC, mode bits all zero means something different, so I do not think that
would fly. If we really wanted to do this "intent-to-add" properly, we
probably should give one of the flag bits in the in-core index structure.
Unlike on-disk flag bits, they are not scarce resources anymore these
days.