[sbe][sharding] Expected 1 chunk skip but saw none in shard3.js

var e = a.find().explain("executionStats").executionStats;

assert.eq(3, e.nReturned, "ex1");

assert.eq(0, e.totalKeysExamined, "ex2");

assert.eq(4, e.totalDocsExamined, "ex3");

var chunkSkips = 0;

for (var shard in e.executionStages.shards) {

    var theShard = e.executionStages.shards[shard];

    chunkSkips += getChunkSkips(theShard.executionStages);

}

assert.eq(1, chunkSkips, "ex4"); // <----- fails

[js_test:shard3] uncaught exception: Error: [1] != [0] are not equal : ex4 :

[js_test:shard3] doassert@src/mongo/shell/assert.js:20:14

[js_test:shard3] assert.eq@src/mongo/shell/assert.js:179:9

[js_test:shard3] @jstests/sharding/shard3.js:91:1

[js_test:shard3] @jstests/sharding/shard3.js:1:2

[js_test:shard3] failed to load: jstests/sharding/shard3.js

[js_test:shard3] exiting with code -3

/**

 * Get the number of chunk skips for the BSON exec stats tree rooted at 'root'.

 */

function getChunkSkips(root) {

    if (root.stage === "SHARDING_FILTER") {

        return root.chunkSkips;

    } else if ("inputStage" in root) {

        return getChunkSkips(root.inputStage);

    } else if ("inputStages" in root) {

        var skips = 0;

        for (var i = 0; i < root.inputStages.length; i++) {

            skips += getChunkSkips(root.inputStages[0]);

        }

        return skips;

    }

    return 0;

}