Cannot load Stored Searches that use 'IS NULL' filter

To recreate on jenny8:

1. Log in as a user with access to at least 1 subject.
2. Go to Browse > Data > Subjects
3. Click the 'Gender' column, and do a filter for 'IS NULL'.
4. Save as a new stored search.
5. Go to a different page, and then select this new search from the top dropdown. This should fail to load.

I've gotten this to fail with a few different data types and columns filtering on, and what all of the failures have in common is that the filter being used is 'IS NULL', so I'm confident that's the culprit. In the logs, we get this:

{code}
2017-03-06 12:49:13,761 [ajp-bio-8009-exec-75] ERROR org.nrg.xnat.restlet.resources.search.SearchResource - Failed POST
java.lang.NullPointerException
at org.nrg.xdat.om.XdatCriteria.buildDisplaySearchCriteria(XdatCriteria.java:93)
at org.nrg.xdat.security.XdatCriteriaSet.getDisplaySearchCriteria(XdatCriteriaSet.java:60)
at org.nrg.xdat.security.XdatCriteriaSet.getDisplaySearchCriteria(XdatCriteriaSet.java:71)
at org.nrg.xdat.om.XdatStoredSearch.getDisplaySearch(XdatStoredSearch.java:181)
at org.nrg.xnat.restlet.resources.search.SearchResource.handlePost(SearchResource.java:182)
at org.restlet.Finder.handle(Finder.java:357){code}