Description of problem:
Imagine a situation when you phase out RHEL5 ks trees, but you have still RHEL5 ks profiles present, one of ks profile might have ticked "Always use the newest Tree for this base channel. "Newest" is determined by the date it was last modified.". If such situation happens then Taskomatic will be doomed, failing every single minute with IndexOutOfBoundsException throwed by KickstartFactory.getNewestTree() call.

Version-Release number of selected component (if applicable):
Satellite-5.6.0-RHEL5-re20130927.0
satellite-schema-5.6.0.19-2.el5sat

How reproducible:
100%

Steps to Reproduce:
0. Sync ks trees for any major rhel release, e.g. rhel5 
1. Create rhel5 ks profile having ticked "Always use the newest Tree for this base channel. "Newest" is determined by the date it was last modified."

2. Phase out rhel5 kickstartable trees
# mv /var/satellite/rhn/kickstart/ks-rhel-x86_64-server-5* /tmp/

3. Taskomatic daemon repeatedly failing every single minute:
# tail -f /var/log/rhn/rhn_taskomatic_daemon.log

INFO   | jvm 1    | 2014/06/24 06:34:00 | 2014-06-24 06:34:00,143 [DefaultQuartzScheduler_Worker-6] ERROR com.redhat.rhn.taskomatic.task.CobblerSyncTask - RuntimeExceptioneError trying to sync to cobbler: null
INFO   | jvm 1    | 2014/06/24 06:34:00 | java.lang.IndexOutOfBoundsException
INFO   | jvm 1    | 2014/06/24 06:34:00 | 	at java.util.LinkedList.get(LinkedList.java:517)
INFO   | jvm 1    | 2014/06/24 06:34:00 | 	at com.redhat.rhn.domain.kickstart.KickstartFactory.getNewestTree(KickstartFactory.java:123)
INFO   | jvm 1    | 2014/06/24 06:34:00 | 	at com.redhat.rhn.taskomatic.task.CobblerSyncTask.execute(CobblerSyncTask.java:89)
INFO   | jvm 1    | 2014/06/24 06:34:00 | 	at com.redhat.rhn.taskomatic.task.RhnJavaJob.execute(RhnJavaJob.java:82)
INFO   | jvm 1    | 2014/06/24 06:34:00 | 	at com.redhat.rhn.taskomatic.TaskoJob.execute(TaskoJob.java:169)
INFO   | jvm 1    | 2014/06/24 06:34:00 | 	at org.quartz.core.JobRunShell.run(JobRunShell.java:216)
INFO   | jvm 1    | 2014/06/24 06:34:00 | 	at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:549)
INFO   | jvm 1    | 2014/06/24 06:34:00 | 2014-06-24 06:34:00,143 [DefaultQuartzScheduler_Worker-6] ERROR com.redhat.rhn.taskomatic.task.CobblerSyncTask - re-throwing exception since we havent yet.
INFO   | jvm 1    | 2014/06/24 06:34:00 | 2014-06-24 06:34:00,144 [DefaultQuartzScheduler_Worker-6] ERROR com.redhat.rhn.taskomatic.task.CobblerSyncTask - 
INFO   | jvm 1    | 2014/06/24 06:34:00 | 2014-06-24 06:34:00,144 [DefaultQuartzScheduler_Worker-6] ERROR com.redhat.rhn.taskomatic.task.CobblerSyncTask - 

3b.@webui you can check cobbler-sync-bunch results (/rhn/admin/BunchDetail.do?label=cobbler-sync-bunch): FAILED


Actual results:
throwed Exception, taskomatic blocked by repeatedly throwed Exceptions


Expected results:
no Exceptions, taskomatic running its tasks


Additional info:
KickstartFactory.java:123 
            return trees.get(trees.size() - 1);       <- size can be sometimes 0:-)