Gurjeet has mentioned that eb.rel cannot be modified by another process since the value or memory is in the local stack, and I believe he's correct.
If the pointed Relation had been blown out, eb.rel would be left dangling, not nullified. However, I don't believe this situation happens (or it shouldn't happen) as the entire relation should already be locked.
Yeah, Gurjeet is right. I had a thinko here. eb.rel should not be NULL pointer in any case. And as we've acquired the lock for it, it should not have been closed. So I think we can remove the check for eb.rel in the two places.
