SVNException cause is a SVNErrorMessage in many cases, 
which encapsulate the root SVNException
upgrade svnkit to 1.7.6
typo in javadoc
[FIXED JENKINS-16217] Take into account the svn:externals of a project when looking for projects to trigger from a post-commit hook.
[FIXED JENKINS-13790] Use the native SVNKit ISVNExternalsHandler to pick up the svn:externals URLs.
due to https://github.com/jenkinsci/svnkit/commit/bfb18dbbc69bcc6af11c3998bba0abe5c7ff082e
svnkit now return "" for directory root when listing directories in repository