effect of xz compression change on deltaiso users

[Andre Robatino]

Jonathan Dieter explained to me a more robust procedure for obtaining the rpms
used to modify F14 to use the new compression. First install/update to the new
xz packages. Then download the latest F15 deltarpm src package, and run
"rpmbuild --rebuild --clean deltarpm*.src.rpm" to generate the binary rpms.
(Having the new xz packages installed first is necessary for the generated rpms
to use the new compression.) This should work with newer versions of F15's
deltarpm, and also work on F13. In fact, instead of downloading the xz binaries
from Koji, one could download the latest F15 xz src package, build those for
F13/F14, install/update them, then build the deltarpm packages.

There is currently a bug in the F15/Rawhide version of deltarpm (
https://bugzilla.redhat.com/show_bug.cgi?id=677578 ) which prevented me from
creating working deltas for TC1->TC2. Michael Young quickly provided a patch,
and using it and the above procedure I was able to build working deltas. The bug
only affects makedeltaiso, not applydeltaiso, so these can be used even if the
unpatched version of deltarpm is installed.