Stephen was kind enough to shine the light on how to fix this problem for SVN 1.1.4 on the Debian 3.1 Webmin
VPS (well, really it's a workaround for the stable branch of Debian 3.1 Sarge). As root you can relink /dev/random to point to /dev/urandom, which is good enough for SVN purposes. For other purposes, consider the lag of using /dev/random while waiting for entropy if you need lots of random numbers ... /dev/urandom is much faster in general.
Of course, if you really need /dev/random, this isn't good enough, but I don't really need it so far. Stephen has indicated that this issue will be addressed at the
VPS level, so meanwhile this is a transparent solution for my Debian
VPS.