Hudson does not handle subversion new external format introduced with 1.5, and
in particular relative directories.

For example, the following repository cannot be checked out properly:
root
proj1
lib/...
proj2
X lib

with svn:externals set in proj2 to:
$ svn propget svn:externals .
../proj1/lib lib

The fix might be to upgrade svnkit to 1.2.1 (where is the patch used to produce
svnkit-1.2.0-hudson-3 ?). At least, a workaround here was to replace
svnkit-1.2.0-hudson-3 with svnkit-1.2.1 and comment the change introduced to fix
#1539.

Index: core/src/main/java/hudson/scm/SubversionUpdateEventHandler.java
===================================================================
— core/src/main/java/hudson/scm/SubversionUpdateEventHandler.java (revision 13571)
+++ core/src/main/java/hudson/scm/SubversionUpdateEventHandler.java (working copy)
@@ -115,9 +115,9 @@
}
} else if (action == SVNEventAction.UPDATE_EXTERNAL) {
// for externals definitions

• SVNExternal ext = event.getExternalInfo();
• if(ext==null) {
• // prepare for the situation where the user created their own
  svnkit
  +// SVNExternal ext = event.getExternalInfo();
  +// if(ext==null) {
  +// // prepare for the situation where the user created their
  own svnkit
  File jarFile = null;
  try { jarFile = Which.jarFile(SVNEvent.class); @@ -125,14 +125,14 @@ // ignore this failure }

  out.println("AssertionError: appears to be using unpatched
  svnkit at "+ jarFile);

• } else { - out.println(Messages.SubversionUpdateEventHandler_FetchExternal( - ext.getResolvedURL(), ext.getRevision().getNumber(), event.getFile())); - //#1539 - an external inside an external needs to have the path appended - externals.add(new SubversionSCM.External(modulePath + "/" + path.substring(0 - ,path.length() - ext.getPath().length()) - ,ext)); - }

  +// } else

  { +// out.println(Messages.SubversionUpdateEventHandler_FetchExternal( +// ext.getResolvedURL(), ext.getRevision().getNumber(), event.getFile())); +// //#1539 - an external inside an external needs to have the path appended +// externals.add(new SubversionSCM.External(modulePath + "/" + path.substring(0 +// ,path.length() - ext.getPath().length()) +// ,ext)); +// }

  return;
  } else if (action == SVNEventAction.UPDATE_COMPLETED) {
  /*