Is resetting the codec_tag the right thing to do?

[daveisfera]

Overview

I'm getting this warning when re-muxing a video:

Stream HEVC is not hvc1, you should use tag:v hvc1 to set it.

Expected behavior

Re-muxing (especially using a template) would copy the values and maintain what already exists in the input

Actual behavior

Value cleared and the underlying processing warns about the "missing" value

Investigation

And I tracked it down to the codec_tag being reset to 0 when using a template:
825809c

Research

I have done the following:

• Checked the PyAV documentation
• Searched on Google
• Searched on Stack Overflow
• Looked through old GitHub issues
• Asked on PyAV Gitter
• ... and waited 72 hours for a response.

Additional context

This is an old change that I don't see details about the motivation for doing it, so there might be a good reason to keep it, but at least in my use case, it causes a problem rather than fixing anything