Re: support for large packs and 64-bit offsets

"Shawn O. Pearce" [off-list ref] writes:

Sure, fine.  But I think you missed my point above - right now if
we move the SHA-1 table out of the .idx file I'm not sure we know
how to support the dumb clients *at all*.  Even if they understand
the latest-and-greatest file formats...

We do an incremental .keep pack for packs 100 objects or more.
If .idx omits SHA-1 values but keeps the crc and offset, that
would be around 12 bytes per object (but you may need an index
into the real SHA-1 table in the .pack file, I dunno) so that
would be 1200 bytes.  If we duplicate SHA-1 table also in .idx
that would make it 32-byte per object, totalling 3200 bytes,
which admittedly is near 3-fold increase, but it may be worth if
we want to avoid the hassle.