typed: Replace duplicates rather than merging

Author: apelisse

Diff for: typed/merge.go

@@ -300,7 +300,9 @@ func (w *mergingWalker) indexListPathElements(t *schema.List, list value.List) (
 			// this element.
 			continue
 		}
-		if _, found := observed.Get(pe); !found {
+		if _, found := observed.Get(pe); found {
+			observed.Insert(pe, value.NewValueInterface(nil))
+		} else {
 			observed.Insert(pe, child)
 		}
 		pes = append(pes, pe)

Diff for: typed/merge_test.go

@@ -469,8 +469,8 @@ var mergeCases = []mergeTestCase{{
 		`{"atomicList":["a","a"]}`,
 	}, {
 		`{"list":[{"key":"a","id":1,"bv":true},{"key":"b","id":2},{"key":"a","id":1,"bv":false,"nv":2}]}`,
-		`{"list":[{"key":"a","id":1,"nv":3}, {"key":"c","id":3},{"key":"b","id":2}]}`,
-		`{"list":[{"key":"a","id":1,"bv":true,"nv":3},{"key":"c","id":3},{"key":"b","id":2}]}`,
+		`{"list":[{"key":"a","id":1,"nv":3},{"key":"c","id":3},{"key":"b","id":2}]}`,
+		`{"list":[{"key":"a","id":1,"nv":3},{"key":"c","id":3},{"key":"b","id":2}]}`,
 	}, {
 		`{"list":[{"key":"a","id":1,"nv":1},{"key":"a","id":1,"nv":2}]}`,
 		`{"list":[]}`,