[leo_manager] already_started always appeared in error.log on managers

[mocchira]

I don't know exactly when but at some point
the below error has always appeared when starting a cluster.
no problem the cluster itself.

on master

[E]     manager_0@127.0.0.1     2016-12-27 13:47:41.210637 +0900        1482814061      leo_manager_sup:create_mnesia_tables_1/2        287     [{cause,{badmatch,{error,{already_started,mnesia}}}}]

and on slave

[E]     manager_1@127.0.0.1     2016-12-27 13:47:43.211639 +0900        1482814063      null:null       0       Error in process <0.936.0> on node 'manager_1@127.0.0.1' with exit value: {{badmatch,{error,{already_started,mnesia}}},[{leo_manager_sup,create_mnesia_tables_2,2,[{file,"src/leo_manager_sup.erl"},{line,305}]}]}