Since r880264, --record-only merges actually drive the editor and apply
svn:mergeinfo diffs (see http://svn.haxx.se/dev/archive-2009-09/0520.shtml).
This makes --record-only merges transitive.
All well and good, but if the applied diff adds explicit mergeinfo to a subtree
that had none prior to the merge, no mergeinfo describing the --record-only
merge itself is recorded on the added subtree mergeinfo. This is *very* similar
to issue #3975.
This bug has occurred in our own repository, see
http://svn.haxx.se/dev/archive-2011-08/0025.shtml
Bug
Major