I'm not super familiar with this script so I'm going to assume your testing was good. Pushed to master as e28acf0.
base path does not work with svn-hook-postcommit-review
Review Request #1875 — Created Oct. 28, 2010 and submitted
I realize this is a contributed script and probably isn't all that supported but the base path parameter in /contrib/tools/svn-hook-postcommit-review is not functioning. I get an error from post-review showing that it included the quotes in the paths it passed to svn diff and other commands (forgot to copy/paste). I attached a patch to not pass the quotes to those commands (first time creating a git patch).
Tested on centos 5 64bit with svn 1.6.12, mod dav svn, reviewboard 1.5.