Add query for gate-devstack-bashate xen functions fails

31 hits in 24 hours, check and gate, all fails.

I'm not sure what triggered this as the xen functions
script in devstack hasn't changed recently, bashate
hasn't done a release recently, and devstack has been
gating on bashate for a couple of weeks now.  Maybe
something changed in infra?

Change-Id: I9f926ff70d563e5261439580b2e39320f9a580a4
Related-Bug: #1365590