Audio issue: Raspbian Stretch + 3.5mm Audio Jack + GstPlayer

[nicolas....@gmail.com]

I found an audio issue while using the 3.5mm audio jack and Raspbian Stretch Lite. The problem is present in Stretch and not in Jessie. I've only noticed this when I was working in the development of a Kivy app. I think the issue was introduced with this change:
viewtopic.php?f=29&t=195178
viewtopic.php?f=29&t=136445

I documented the error and provided a way to reproduce it here:
https://github.com/stupidusername/KSTest

I posted this on the Raspbian forums but I got no answer.

It would be helpful to determine where the error is coming from. Right now I don't know if this happens because there is a bug in the Raspbian audio driver or in the Kivy audio player implementation.

Any help would be appreciated. Thank you!