"select":["props"] doesn't work of getEdges

According to the docs of s2graph, users can use "select" to decide what in the Edge data fields should be included when using getEdges 

But when I used getEdges ,and I set "select":["props"] in the getEdges’s command according to "Query Level Options",but it did not get the right result, the total "props" result is "{}", 
actually，the "select" can affect the child filed of “props”，but can not affect the total "props" field。

may be it should be improved。