This is a python script recording merge operations across branches.
It enables one to see the available ranges of changesets that can be merged (
svnmerge avail) and then actually merge them (
svnmerge merge). Revisions that should be prevented from being merged can be explicitly blocked (
Similar functionalities are expected to be available in Subversion itself, with version 1.5 (or later).
See also: SvnWiki:Svnmerge.py