'svnrdump load' can commit changes with the wrong properties, or error out, when
loading a non-delta dumpfile produced by 'svnadmin dump'.
When loading an add-with-history node record from a non-deltas dumpfile, on
reading the new properties, the dumpfile parser first calls the rdump load
editor's 'remove_node_props' method. This method was attempting to issue
property delete instructions for each existing property, but it was always
trying to fetch the existing props from PATH@HEAD. In a copy situation, it needs
to look at COPYFROM_PATH@COPYFROM_REV instead. If PATH@HEAD didn't exist it
would error out, and if it did exist it would then proceed to delete each of the
props found there, which may not include all of the props that the new node will
inherit from its copy source.
The two possible wrong behaviours are:
(1) it will silently make successful commits where copied nodes have the wrong
set of properties (specifically, it will fail to delete some or all of the props
that were present on the copy source and that should be deleted on the copy target);
(2) it will error out.