bufferBehind is being overridden by image adaptation set's segment duration

[littlespex]

Have you read the FAQ and checked for duplicate open issues?
Yes

What version of Shaka Player are you using?
4.2.x

Can you reproduce the issue with our latest release version?
Yes

Can you reproduce the issue with the latest code from main?
Yes

Are you using the demo app or your own custom app?
Both

If custom app, can you reproduce the issue using our demo app?
Yes

What browser and OS are you using?
Chrome macOs

For embedded devices (smart TVs, etc.), what model and firmware version are you using?
WebKit Foxtel

What are the manifest and license server URIs?

Available upon request

What configuration are you using? What is the output of player.getConfiguration()?

Default

What did you do?

Load a manifest that has an image adaptation set containing a SegmentTemplate with a duration larger than 60 (the default bufferBehind value).

What did you expect to happen?
The value of bufferBehind should be 60, or what ever value was passed in through the config.

What actually happened?

The value is the duration of the image segment template. While this is expected behavior if a video or audio segment's duration is longer than the configured value, we don't expect image adaptations to apply as they don't actually use the buffer.