1st, removed all related SVN plugins and connectors.
Then reinstall again SVN plugins & connectors.
But existing SVN projects won't appear to have SVN enabled.
http://stackoverflow.com/questions/166220/restore-eclipse-subversion-project-connection
Edit: is not applicable to Neon.2.
Trying for mars and successful:
https://docs.google.com/document/d/12Fh-NqSj4-shRVtlVwvjEOqiqMwlsvvfOGh1WpC_U2s/edit?usp=sharing
