Ignore result of supervisor calls.
Ignore result of supervisor calls.

Resolves:

riak_kv_mrc_pipe.erl:287: Expression produces a value of type 'ok' | {'error','not_found' | 'simple_one_for_one'}, but this value is unmatched
riak_kv_mrc_pipe.erl:876: Expression produces a value of type 'ok' | {'error','not_found' | 'simple_one_for_one'}, but this value is unmatched

andytill/riak_kv