Something is broken in repack

[Paolo Bonzini]

> When I returned to the computer this morning, the repack was 
> completed... with a 1.3GB pack instead.
> 
> So... The gcc repo apparently really needs a large window to efficiently 
> compress those large objects.

So, am I right that if you have a very well-done pack (such as gcc's), 
you might want to repack in two phases:

- first discarding the old deltas and using a small window, thus 
producing a bad pack that can be repacked without humongous amounts of 
memory...

- ... then discarding the old deltas and producing another 
well-compressed pack?

Paolo