Add an XFAIL regression test for issue 3515, a DAV client cannot
refresh a lock using a LOCK request with an If: header.

Patch by: Sergey Raevskiy <sergey.raevskiy{_AT_}visualsvn.com>


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1584576 13f79535-47bb-0310-9956-ffa450edef68