Remove dead variable bothsds from object.c.

Thanks to @run and @badboy for spotting this.
Triva: clang was not able to provide me a warning about that when
compiling.

This closes #1024 and #1207, committing the change myself as the pull
requests no longer apply cleanly after other changes to the same
function.
Fix replicationFeedSlaves() off-by-one bug.

This fixes issue #1221.
Test: regression test for issue #1221.