In case pybot is started with the –T option, then the name of the output.xml is something like output-20131031-160127.xml
Unfortunately the file is then not found during publishing of the test results.
In the Jenkins job/plugin configuration Output xml name is configured as output.xml.
The help says:
Splitted files will be copied automatically. If file name is specified output.xml then all output-xxx.xml will be saved.
So I assume output-160127.xml would work, but output-20131031-160127.xml does not.

Debug: D:\robot\robotLogs\V.LTE1442.005\debug-20131031-160127.txt
Output: D:\robot\robotLogs\V.LTE1442.005\output-20131031-160127.xml
Log: D:\robot\robotLogs\V.LTE1442.005\log-20131031-160127.html
Report: D:\robot\robotLogs\V.LTE1442.005\report-20131031-160127.html
[htmlpublisher] Archiving HTML reports...
[htmlpublisher] Archiving at BUILD level D:\robot\robotLogs\V.LTE1442.005 to /export/Jenkins/.jenkins/jobs/V.LTE1442.005/builds/2013-10-31_16-01-26/htmlreports/HTML_Report
Robot results publisher started...
-Parsing output xml:
Failed!
hudson.AbortException: No files found in path D:\robot\robotLogs\V.LTE1442.005 with configured filemask: output.xml
at hudson.plugins.robot.RobotParser$RobotParserCallable.invoke(RobotParser.java:71)
at hudson.plugins.robot.RobotParser$RobotParserCallable.invoke(RobotParser.java:51)
at hudson.FilePath$FileCallableWrapper.call(FilePath.java:2420)
at hudson.remoting.UserRequest.perform(UserRequest.java:118)
at hudson.remoting.UserRequest.perform(UserRequest.java:48)
at hudson.remoting.Request$2.run(Request.java:326)
at hudson.remoting.InterceptingExecutorService$1.call(InterceptingExecutorService.java:72)
at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
at java.util.concurrent.FutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Build step 'Publish Robot Framework test results' changed build result to FAILURE