Comment 6 for bug 1813147

Cinder hit "Not a text type application/octet-stream" pretty consistently after switching to stestr. The trigger for it seemed to be any time a test had a very large amount of stderr output. Trienish and I tried to track down exactly where that was causing an issue, but unfortunately were not able to find what was causing the issue. It seemed to be something with the py3 handling of the output stream.

We "fixed" it in Cinder by cleaning up the amount of output generated from unit tests. Once I got rid of warning output and unnecessary logging to the point that there wasn't a lot of stdout/stderr generated, we stopped hitting whatever threshold was causing the error to surface.