Author: Michael Schroeder <mls(a)suse.de>
Date: 2013-09-05 (Thu, 05 Sep 2013)
[backend] drop the inode number from the deltaid hash, it breaks if the tree is copied
The inode is good for internal stuff, but bad for deltas, as deltas
get published and a redone delta is newly signed and thus end up
different than the old delta.
Copy over the old delta if we have one to ease migration.