DF-2532: SURVIVED (fix applied)
DF-2532: constructing impossible state
DF-2532: calling xa_start(tag, NULL, 1) with empty spanq, B_FAILONDIS set, tag->bio=0xfffff8004f1e86d0
DF-2532: xa_start will find no spans (trans=NULL) -> goto skip
DF-2532: B_FAILONDIS set -> else branch -> xa_done(tag,1)
DF-2532: xa_done: with fix, KKASSERT is gone; xa_release handles tag->bio
DF-2532: survived (INVARIANTS off?)
--- Guest still up, no panic ---