Merging in Subversion

Now I've done my second Subversion merge using the new 1.5 mergeinfo, and both times I've hit the same problem when trying to "reintegrate" the branch. Subversion complains:

   Some revisions have been merged under it that have not been merged
  into the reintegration target; merge them first, then retry.

This post on CollabNet's Subversion blog helped me out. The problem boils down to the fact that there is "subtree" mergeinfo in the branch and/or trunk which prevents the merge from completing. Usually you can safely delete the subtree merge info:

   svn propdel svn:mergeinfo <subtree> -R

I honestly don't understand why this issue arises or why Subversion is not able to resolve it. Despite having mergeinfo is much better than not having it, I can't help feeling that this is a kludge to handle a feature which Subversion wasn't at all designed for.