Since I keep forgetting what the tool is called and how to use it:
svnrdump is a tool that can dump a remote svn repostory to a text file and also load that text file into a different remote svn repository. It comes with the TortoiseSVN installation (but is really part of the standard Subversion tool set).
My use case is migrating projects from SourceForge to OSDN. On the OSDN side the option “Allow to modify revision properties for project members” must be enabled which is available on the Subversion -> Admin page. It really takes a few minutes for that option to become active.
To dump a repository:
svnrdump dump https://source.site/some/repository/ > somerepository.dump
To load a repository:
svnrdump load https://dest.site/some/repository < somerepository.dump
Of course, since svnrdump writes to stdout and reads from stdin, it should be possible to do both in one go:
svnrdump dump https://source.site/some/repository/ | svnrdump load https://dest.site/some/repository
But I have never tried it. I prefer getting a dump file first, just in case anything goes wrong.