Inconsistent query results

Following word count query returns inconsistent result with Spock.

Same inconsistent results are observed with 4.6 equivalent query (with pure sub-query, not subquery expression) on spock build. This 4.6 query gives consistent results (as in run2)  in the 4.6 release.

Also, note that I only get these two variants of results and not any other 3rd variant.

You may have to rerun the query 5 times or so to see the inconsistent results.

spock version using subquery expr (Build: 2031, on Mac 10.12.3 (Sierra)):

========================================================

SELECT w, cnt
FROM ARRAY split FOR i IN (SELECT raw name
FROM `travel-sample`
WHERE type = "hotel") END AS words
UNNEST words w
GROUP BY w LETTING cnt = COUNT(w)
ORDER BY cnt DESC;

4.6 version:

========

SELECT w, cnt
FROM (SELECT raw n1
FROM `travel-sample` t
UNNEST split(t.name) n1
WHERE t.type = "hotel") AS w
GROUP BY w LETTING cnt = COUNT(w)
ORDER BY cnt DESC

LIMIT 10;

Run1 results:

===========

[
{
"cnt": 273,
"w": "Hotel"
},
{
"cnt": 106,
"w": "Inn"
},
{
"cnt": 78,
"w": "The"
},
{
"cnt": 48,
"w": "House"
},
{
"cnt": 31,
"w": "Hostel"
},
{
"cnt": 27,
"w": "Birmingham"
},
{
"cnt": 25,
"w": "Holiday"
},

Run2 results (obtained with 4.6):

=========================

[
{
"cnt": 315,
"w": "Hotel"
},
{
"cnt": 114,
"w": "Inn"
},
{
"cnt": 95,
"w": "The"
},
{
"cnt": 51,
"w": "House"
},
{
"cnt": 38,
"w": "Hostel"
},
{
"cnt": 28,
"w": "Birmingham"
},
{
"cnt": 27,
"w": "Holiday"
},