I have just switched the source code from Subversion to Git. The code can now be accessed on github, which provides a nicer interface for the history of commits and many more features.
Your svn local copy should be replaced by a local fork of the git repository. Everything is explained on the Solarus github page, but to be short, use the following command to download the code (obviously, git needs to be installed):
git clone git://github.com/christopho/solarus.git
Note: the SVN repository is still available but is now obsolete. New commits are only made on the Git repository. The SVN repository remains at revision 1443.