Description of problem:
Spacewalk 1.9 has new functionality that allows a kickstart profile to stay attached to the newest tree available. Currently however the kickstart profile will attach itself to the kickstart tree with the last alphabetical label, not the most recent last_modified date. 

How reproducible:
always


Steps to Reproduce:
1. create a kickstart profile that is set to stay updated to the latest kickstart tree (distribution)
2. create or modify a kickstart tree
  
Actual results:
The kickstart profile attaches itself to the kickstart tree with the last alphabetically-ranked label

Expected results:
The kickstart profile attaches itself to the newest kickstart tree.