Ensure there is no compatibility issues between plug-in versions with...

Ensure there is no compatibility issues between plug-in versions with different SVN API supported (bug 488653)
https://bugs.eclipse.org/bugs/show_bug.cgi?id=488653

git-svn-id: https://dev.eclipse.org/svnroot/technology/org.eclipse.subversive/trunk@21541 ee007c2a-0a25-0410-9ab9-bf268980928c