How to remove empty revisions from existing svn dump file?
this is the command line that i use.. it seems to work pretty well.
svnadmin dump <path_to_repo> | svndumpfilter2 <path_to_repo> [list of paths to keep] --renumber-revs --drop-empty-revs |bzip2 --best > svn_dumpfile_full.bz
the "list of path to keep" can be as simple as trunk
but it does require you to have access to the svn server directly.