svn 1.4改变了工作拷贝和仓库的格式

之前用的debian testing, 现在换用ubuntu 6.10后发现svn命令用不了，运行后显示：
svn: 本客户端已过时，无法存取工作拷贝“.”；请取得更新版的 Subversion 客户端

经过比较，原来debian testing中的subversion是1.4.2, 而ubuntu 6.10 中的是1.3.2, 因为subversion从1.4开始改变了工作拷贝和仓库的格式，从而导致之前的工作拷贝(1.4版建立的)在1.3版的svn中无法使用. ubuntu不是基于debian unstable的吗？怎么subversion版本比debian testing还旧？ 真不明白。

Subversion 1.4 Release Notes 中对此有说明：
Working Copy and Repository Format Changes

Due to certain improvements and bugfixes made to the working copy library, the version number of the working copy format has been incremented. This means that Subversion clients earlier than 1.4 will not be able to work with working copies produced by Subversion 1.4. Similarly, the repository format has changed as well, meaning that pre-1.4 Subversion tools that normally access a repository directly (e.g. svnserve, mod_dav_svn, svnadmin) won't be able to read a repository originally created by Subversion 1.4.

WARNING: if a Subversion 1.4 client encounters a pre-1.4 working copy, it will automatically upgrade the working copy format as soon as it touches it, making it unreadable by older Subversion clients. If you are using several versions of Subversion on your machine, you need to be careful about which version you use in which working copy, to avoid accidentally upgrading the working copy format. This "auto upgrade" feature, however, does not occur with the new repository format.