Janitor fails to bring bucket online in a mixed cluster (watson -> vulcan)

While upgrading from watson to vulcan, an attempt to create a bucket in the mixed cluster mode fails to bring the bucket online. The following failure is seen while negotiating the features using the HELO command:

=========================CRASH REPORT=========================$
  crasher:$
    initial call: janitor_agent:init/1$
    pid: <0.22652.0>$
    registered_name: 'janitor_agent-test'$
    exception exit: {{{{case_clause,$
                        {error,$
                         {{{badmatch,$
                            {error,$
                             {function_clause,$
                              [{dcp_proxy,$
                                'do_negotiate_features/4-blc$^0/1-0',$
                                [undefined],$
                                [\{file,"src/dcp_proxy.erl"},\{line,283}]},$
                               {dcp_proxy,do_negotiate_features,4,$
                                [\{file,"src/dcp_proxy.erl"},\{line,283}]},$
                               {dcp_proxy,negotiate_features,5,$
                                [\{file,"src/dcp_proxy.erl"},\{line,261}]},$
                               {dcp_proxy,connect,5,$
                                [\{file,"src/dcp_proxy.erl"},\{line,251}]},$
                               {dcp_proxy,maybe_connect,2,$
                                [\{file,"src/dcp_proxy.erl"},\{line,210}]},$
                               {dcp_producer_conn,init,2,$
                                [{file,"src/dcp_producer_conn.erl"},$
                                 {line,31}]},$
{dcp_proxy,init,1,$
                                [\{file,"src/dcp_proxy.erl"},\{line,57}]},$
                               {gen_server,init_it,6,$
                                [\{file,"gen_server.erl"},\{line,304}]}]}}},$
                           [{dcp_replicator,init,1,$
                             [\{file,"src/dcp_replicator.erl"},\{line,50}]},$
                            {gen_server,init_it,6,$
                             [\{file,"gen_server.erl"},\{line,304}]},$
                            {proc_lib,init_p_do_apply,3,$
                             [\{file,"proc_lib.erl"},\{line,239}]}]},$
                          {child,undefined,$
                           {'n_0@10.17.1.133',false},$
                           {dcp_replicator,start_link,$
                            ['n_0@10.17.1.133',"test",false]},$
                           temporary,60000,worker,$
                           [dcp_replicator]}}}},$
                       [{dcp_sup,start_replicator,2,$
                         [\{file,"src/dcp_sup.erl"},\{line,54}]},$
                        {dcp_sup,'manage_replicators/3-lc$^3/1-3',2,$
                         [\{file,"src/dcp_sup.erl"},\{line,81}]},$
                        {dcp_replication_manager,handle_call,3,$
                         [\{file,"src/dcp_replication_manager.erl"},\{line,87}]},$
                        {gen_server,handle_msg,5,$
                         [\{file,"gen_server.erl"},\{line,585}]},$
                        {proc_lib,init_p_do_apply,3,$
                         [\{file,"proc_lib.erl"},\{line,239}]}]},$
                      {gen_server,call,$
                       ['dcp_replication_manager-test',$
                        {manage_replicators,$
                         ['n_0@10.17.1.133','n_1@127.0.0.1','n_2@127.0.0.1’,$