union all bug

[czpmango]

The result of a UNION ALL cannot be passed by a pipe.

reproduce:

(czp@nebula) [nba]> lookup on player where player.name=="Tim Duncan" | yield $-.VertexID
+--------------+
| $-.VertexID  |
+--------------+
| "Tim Duncan" |
+--------------+
Got 1 rows (time spent 1823/2028 us)

(czp@nebula) [nba]> lookup on player where player.name=="Tim Duncan" union all lookup on player where player.age==42
+----------------+
| VertexID       |
+----------------+
| "Tim Duncan"   |
+----------------+
| "Tim Duncan"   |
+----------------+
| "Vince Carter" |
+----------------+
Got 3 rows (time spent 2350/2581 us)

(czp@nebula) [nba]> lookup on player where player.name=="Tim Duncan" | go from $-.VertexID over like
+-----------------+
| like._dst       |
+-----------------+
| "Manu Ginobili" |
+-----------------+
| "Tony Parker"   |
+-----------------+

(czp@nebula) [nba]> lookup on player where player.name=="Tim Duncan"  | get subgraph 0 steps from $-.VertexID
+----------------------------------------+
| _vertices                              |
+----------------------------------------+
| [("Tim Duncan" :bachelor{} :player{})] |
+----------------------------------------+
Got 1 rows (time spent 2379/2632 us)

(czp@nebula) [nba]> lookup on player where player.name=="Tim Duncan" union all lookup on player where player.age==42 | get subgraph 0 steps from $-.VertexID
[ERROR (-1009)]: SemanticError: different column names to UNION/INTERSECT/MINUS are not supported

(czp@nebula) [nba]> lookup on player where player.name=="Tim Duncan" union all lookup on player where player.age==42  | go from $-.VertexID over like
[ERROR (-1009)]: SemanticError: different column names to UNION/INTERSECT/MINUS are not supported