Sort Row step output wrong result

Hello, here is the details:

I use PDI 4.4.0 community binary on Linux

I have a data file in text format, which contain about 50,000,000 rows.

I load the data and send it to a Sort Row step, I keep sort cache remain on 1,000,000

Then I find the result is wrong.

I change the sort cache to 100,000,000, then I got the right result.

I see on Jira some people report a issue relative sort cache, is this similar? http://jira.pentaho.com/browse/PDI-10580