Description of problem:
If I update directory in configuration channel by webui, then I get page with ISE 500. It's regression against Satellite 5.6

Version-Release number of selected component (if applicable):
spacewalk-java-2.3.8-96.el6sat.noarch

How reproducible:
always

Steps to Reproduce:
1. create channel by webui
2. add directory to this channel by webui
3. try to edit this directory by webui 

Actual results:
ISE 500

Expected results:
without ISE

Additional info:
Exception:
javax.servlet.ServletException: java.lang.NullPointerException
	at org.apache.struts.action.RequestProcessor.processException(RequestProcessor.java:520)
	at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:427)
	at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:228)
	at com.redhat.rhn.frontend.struts.RhnRequestProcessor.process(RhnRequestProcessor.java:102)
...
	at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:291)
	at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:769)
	at org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:698)
	at org.apache.jk.common.ChannelSocket$SocketConnection.runIt(ChannelSocket.java:891)
	at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:690)
	at java.lang.Thread.run(Thread.java:761)
Caused by: java.lang.NullPointerException
	at com.redhat.rhn.manager.configuration.file.ConfigFileData.matchesRevision(ConfigFileData.java:438)
	at com.redhat.rhn.manager.configuration.ConfigFileBuilder.makeNewRevision(ConfigFileBuilder.java:150)
	at com.redhat.rhn.manager.configuration.ConfigFileBuilder.update(ConfigFileBuilder.java:233)
	at com.redhat.rhn.frontend.action.configuration.files.FileDetailsAction.execute(FileDetailsAction.java:81)
	at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:425)
	... 40 more