yum-presto not on by default

[Bill Nottingham]

Andre Robatino (andre at bwh.harvard.edu) said: 
> If I understand correctly what the problem is - that successfully
> xz-uncompressing a file requires being on the same endian arch as the
> one it was compressed on - that's just wrong.  It shouldn't be
> platform-dependent at all.

That is not the issue. There are two issues:

- Compressing a file on different arches, while it produces output
that any arch can decompress, does produce *different* output.
- Compression of xz is not fast.

Bill