MapReduce input lists can't include bucket type without key data [JIRA: RIAK-3248]

[lukebakken]

Source line:

https://github.com/basho/riak_kv/blob/develop/src/riak_kv_mapred_term.erl#L111-L122

Consider the following inputs to MapReduce:

BT = <<"type">>,
B = <<"bucket">>
Inputs = [{{BT, B}, <<"key1">>}, {{BT, B}, <<"key2">>}]

The linked code will not parse this correctly unless KeyData is also present, like this:

BT = <<"type">>,
B = <<"bucket">>
Inputs = [{{{BT, B}, <<"key1">>}, key_data}, {{{BT, B}, <<"key2">>}, key_data}]