The riak_core_gossip:legacy_gossip/0 and related functions have been
stubbed to false in commit d0ea731 ("Permanently disable
legacy gossip"), by Joseph Blomstedt way back in 2013-05-20. It was
merged in at some point before tag 1.4.0.
Sean Cribbs' commit (the one currently being rebased) dates from
2014-04-01. It exists in branch bugfix/sdc/remove-legacy-gossip, and
has not been merged. There is a PR for that, #541.
In this commit, Sean removes the code paths that would have been not
dead if legacy_gossip ever returned 'true', as well as the checks