Dear Maintainer,

If the build environments have different DPKG_DEB_COMPRESSOR_{TYPE,LEVEL}
environment variables, debrebuild fails with a checksum mismatch.

debrebuild sets the environment variables from the buildinfo file
Environment block and since these variables affect reproducibility of
the package, it would make sense to include them.

I've attached a patch that adds these variables to the allow list and
makes debrebuild 'just work' in this case.
It shouldn't affect the official buildinfo files or the resulting builds.

If this approach is not suitable for any reason, let me know and I'm happy
to rework it.

Many thanks,

Serge