[#1321] Fix scroll cursor leak inside searchScroll helper.

[abarre]

I didn't find a way to test this change.
The leak is not visible in the client side but only in the server side during the scroll window.

[elasticmachine]

Since this is a community submitted pull request, a Jenkins build has not been kicked off automatically. Can an Elastic organization member please verify the contents of this patch and then kick off a build manually?

[delvedor]

Thanks for the fix!
Regarding the test, you should add a new test case in this file to verify that the last call (if the conditions are met) is a clear scroll.

[abarre]

I will modify this PR in the next days. I had a quick look at the code and I see that the test code expect that the last request doesn't send a scroll_id in the response.
Can you confirm that this is a mistake and that in real life, all responses contain a scroll id ?

I didn't find the documentation on this point.

[delvedor]

I've checked and the scroll_id is always present in the body, but it can change over time.
I've opened #1331 with the fix and the updated test.
Closing this, thank you a lot for contributing!