As it is explained in the svn book [1] in order to share a repository in a multi user environment, every user should set their umask to 002, to avoid permission problems. Implementing this in debian can be problematic as explained in this bug report [2]. Setting this umask by default is a potential security risk and should be avoided (this is true at least in redhat where every user is member of the user group, in debian we have a better approach where every user a member of of its own user group by default). The solution is to use a wrapper and to put it in /usr/local/bin . The wrapper is actually already being written for you. This is what you have to do:

apt-get install subversion-tools
ln -s /usr/bin/svnwrap /usr/local/bin/svn
ln -s /usr/bin/svnwrap /usr/local/bin/svnserve

since in debian by default /usr/local/bin is looked up before then /usr/bin the two links created above are used instead of the real svn binaries avoiding any problem related to upgrades.

[1] http://svnbook.red-bean.com/en/1.0/ch06s05.html [2] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=24236