It may be due to the property 'subversion_branding.repository_base' pointing to /sf-svnroot instead of the /svnroot directory, which is used by the scm-integration of the csfe installation.
First, check the location of the repository in subversion_branding.repository_base=/sf-svnroot' in /usr/local/sourceforge/runtim/conf/sourceforge.properties.
If it has to be /svnroot, then add an entry that states SUBVERSION_BRANDING_REPOSITORY_BASE=/svnroot
Then re-create a runtime and restart CSFE.