During svn updates or commits, this causes inconsistent synchronization data and the client in Eclipse, confused, ends up throwing errors.
Because the errors cause an abort of the update or commit process, this leaves the repository in a very unstable state, my guess is that it tries to retrieve a name of a file but gets back null, and ends up writing this back to the .svn/entries somehow.
SVN connector is set on "SVNKit 1.7.4-v1 r9190_v20120510_1337 (SVN 1.7.4 compatible, all platforms)".
I arrived on this page because I had the same question.
The steps to fix the issue are select all subclipse plugins and click uninstall.
(Upgrading the working copies is, however, required; Subversion 1.7.0 cannot operate on working copies created or used by earlier Subversions.) Subversion 1.6.x and earlier automatically upgrade working copies when they first touch them.
This behavior can be annoying, if you just want to try out a new release of Subversion without installing it permanently.