When using a tailable cursor, only the first iteration to cursor::end() works and subsequent iteration attempts find nothing. See the attached file for an example.

This is almost certainly a consequence of the way cursors are marked dead in the fix for CXX-1001 and CXX-1100, which should not happen if the cursor is tailable.

I also see that we have no integration tests for tailable cursors, or we'd have caught this breakage earlier.