Filtering clause returns unexpected failure

[xllora]

Given the following data set

/_<c175b457-e6d6-4ce3-8312-674353815720>	"_predicate"@[]	"/some/immutable/id"@[]
/_<c175b457-e6d6-4ce3-8312-674353815720>	"_owner"@[2017-05-23T16:41:12.187373-07:00]	/gid<0x9>
/_<c175b457-e6d6-4ce3-8312-674353815720>	"_subject"@[]	/aid</some/subject/id>
/_<c175b457-e6d6-4ce3-8312-674353815720>	"_object"@[]	/aid</some/object/id>
/_<cd8bae87-be96-41af-b1a8-27df990c9825>	"_object"@[2017-05-23T16:41:12.187373-07:00]	/aid</some/object/id>
/_<cd8bae87-be96-41af-b1a8-27df990c9825>	"_owner"@[2017-05-23T16:41:12.187373-07:00]	/gid<0x6>
/_<cd8bae87-be96-41af-b1a8-27df990c9825>	"_predicate"@[2017-05-23T16:41:12.187373-07:00]	"/some/temporal/id"@[2017-05-23T16:41:12.187373-07:00]
/_<cd8bae87-be96-41af-b1a8-27df990c9825>	"_subject"@[2017-05-23T16:41:12.187373-07:00]	/aid</some/subject/id>
/aid</some/subject/id>	"/some/temporal/id"@[2017-05-23T16:41:12.187373-07:00]	/aid</some/object/id>
/aid</some/subject/id>	"/some/immutable/id"@[]	/aid</some/object/id>
/aid</some/subject/id>	"/some/ownerless_temporal/id"@[2017-05-23T16:41:12.187373-07:00]	/aid</some/object/id>

The following query succeeds as expected.

bql> SELECT ?bn,?p, ?o 
     FROM ?test 
     WHERE { 
          ?bn "_subject"@[,]    /aid</some/subject/id>. 
          ?bn "_predicate"@[,] ?p .
          ?bn "_object"@[,] ?o 
      };

?bn	?p	?o
/_<cd8bae87-be96-41af-b1a8-27df990c9825>	"/some/temporal/id"@[2017-05-23T16:41:12.187373-07:00]	/aid</some/object/id>

[OK] Time spent:  578.963µs

However, when you specify ?o, it fails with a filtering error.

bql> SELECT ?bn,?p  
     FROM ?test 
     WHERE { 
          ?bn "_subject"@[,]    /aid</some/subject/id>. 
          ?bn "_predicate"@[,] ?p . 
          ?bn "_object"@[,] /aid</some/object/id>
      };

[ERROR] planner.Execute: failed to execute insert plan with error failed to fully specify clause { ?bn "_object"@[,] /aid</some/object/id> } for row map[?bn:/_<cd8bae87-be96-41af-b1a8-27df990c9825>]
Time spent:  514.294µs

Given the this is just and update on the query above, this should have not failed and return one row with ?bn and ?p bindings.