miniogw: fix metainfo: invalid direction 0 list error

Calling list.Next() after it has returned false gives an invalid
direction error, a sort of double free type gotcha. libuplink may fix
this in the future but there's no point calling it again after it has
returned false anyways.

Closes #70

Change-Id: I5e6031b50ba88194348c2567b271f3fef92ef2c6

miniogw/gateway.go

@@ -285,7 +285,8 @@ func (layer *gatewayLayer) listObjectsFast(
 
 	limit := limitResults(maxKeys, layer.compatibilityConfig.MaxKeysLimit)
 
-	for limit > 0 && list.Next() {
+	var more bool
+	for more = list.Next(); limit > 0 && more; more = list.Next() {
 		item := list.Item()
 
 		limit--
@@ -302,11 +303,6 @@ func (layer *gatewayLayer) listObjectsFast(
 		return nil, nil, "", list.Err()
 	}
 
-	more := list.Next()
-	if list.Err() != nil {
-		return nil, nil, "", list.Err()
-	}
-
 	if !more {
 		nextContinuationToken = ""
 	}