nginx removes strong etags on gzip compression

[J.R.]

> If that is not doable, then possibly you could patch your nginx to accept
> this invalid header; or possibly you could try some other config-based
> manipulation to make things work the way that you want. I suspect that
> either of those is likely to be more work in the long run than fixing
> the upstream.

Depending on the order of how everything runs, *maybe* it can be captured
with the "headers more" module?

https://github.com/openresty/headers-more-nginx-module

Just a thought... No idea if it would work.