Legacy SVN repository
The old subversion repository is still available to inspect original history of packages. However, all history should have been transferred to the new mercurial and git repositories.
History of legacy SVN repository
Before February 2010, Octave Forge was released a single project including all of its Octave packages. Before 2007, Octave Forge did not even have packages since Octave did not had a package manager yet; all of Octave-Forge was a single extension to Octave. Development of packages were concerted and releases were synced. Because of this, all development happened in a single repository, it was a single project.
As the number of packages increased it became too difficult to coordinate development of the packages, and with the introduction of a package manager in Octave there was no need for that either. Development of packages continued to happen in the single subversion repository.
Eventually subversion became a burden as packages preferred to have its main development happen somewhere else. Between 2013 and 2016, individual packages migrated their history from subversion to a DVCS such as mercurial and git. History of whole package development was migrated to the new repositories.