TIMEDIFF() returns incorrect result

Build tested: 1.4.0-1

[dlee@master centos7]$ cat gitversionInfo.txt
server commit:
67452bc
engine commit:
4d2a159

Autopilot test case: features.functions

ColumnStore returned:

18 select cidx, CTIME, TIMEDIFF(CTIME,'2007-02-28 22:23:0') from datatypetestm order by cidx
19 --------------
20
21 cidx CTIME TIMEDIFF(CTIME,'2007-02-28 22:23:0')
22 1 13:00:00 -838:59:59
23 1 row in set

40 select cidx, CTIME from datatypetestm where TIMEDIFF(CTIME,'2007-02-28 22:23:0') <> 0 order by cidx
41 --------------
42
43 cidx CTIME
44 1 13:00:00
45 1 row in set

reference returned:

18 select cidx, CTIME, TIMEDIFF(CTIME,'2007-02-28 22:23:0') from datatypetestm order by cidx
19 --------------
20
21 cidx CTIME TIMEDIFF(CTIME,'2007-02-28 22:23:0')
22 1 13:00:00 NULL
23 1 row in set

40 select cidx, CTIME from datatypetestm where TIMEDIFF(CTIME,'2007-02-28 22:23:0') <> 0 order by cidx
41 --------------
42
43 Empty set

This test works in 1.2.4-1