I had set proxy.config.http.normalize_ae to 2 and enabled brotli ( br ) compression，

when ats(v9.0.0) had cached both gzip and brotli compressed version of the object,
and if gzip object was generated after brotli one， ats will always return gzip when client supports both gzip and brotli.

steps to reproduce the problem:

1、Accept-Encoding: gzip,br
ats will return br encoding as expected

2、Accept-Encoding: gzip
ats will return gzip encoding as expected

3、Accept-Encoding: gzip,br
**** ats will always return gzip encoding , which should be br encoding. ****

4、Accept-Encoding: br
ats will return br encoding as expected.