I was unable to use the --reintegration flag when trying to merge between two (parent-child) branches. The following message was produced:
merge --reintegrate https://bigdata.svn.sourceforge.net/svnroot/bigdata/branches/bbb_cleanup /home/resendes/workspace/maven_scaleout/bigdata-core
Trying to use an unsupported feature
svn: Retrieval of mergeinfo unsupported by 'https://bigdata.svn.sourceforge.net/svnroot/bigdata'
Hitting the server URL shows that it's running subversion 1.6.6, so I'm assuming that the problem is due to the fact the actual repo's filesystem is based on an older version of SVN.
A quick search seems to imply that this can be done (easily?) with server-side tools: