All files in the .svn directories are processed by the Subversion library, which means all svn clients (and not just TSVN), where they are located as text. Even the .svn folder itself is marked as readonly and hidden. There is a reason why these files are marked as readonly, and you should not deal with this. SVN relies on this.
Update: The fact that you are actually trying to synchronize a working copy implies that you are using version control completely wrong. It is called a working copy, because you must have a copy of it at every station with which you work. And you need to use a separate working copy. Do not sync the same working copy.
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