If I have a sparse checkout of /trunk (say it has subdirectories dir1 and dir2, so I just have a working copy of /trunk/dir1), commit some changes, switch my checkout to a branch, then try to merge the changes I just committed, the mergeinfo property gets revisions marked with "*" in the branch root, and updates mergeinfo in the directory with the changes.
Is there any reason the merge has to have the "*", since there were no changes outside of my working copy?