* Investigate gz files that zgz cannot reproduce. Such files are stored
in the testsuite git branch.
+
* Would be nice to keep a md5sums list of the files in the manifest and
check and error if any are different. The error message from xdelta when
a source file doesn't have the right checksup is fairly obscure and
git://git.debian.org/git/users/kibi-guest/pristine-tar.git , but I have
not yet decided about applying it, since it would bloat the delta files
with a list of all the files and md5sums..
+
* Optimisation: Enhance zgz so it runs multiple compression alternatives
block-by-block in parallell, aborting compressors when they differ
from the target file.