disabling gzip if etag exists in proxy_pass response

Hi,

I'm new to nginx.

Is there a way to disable gzip if proxy_pass reutrns the ETag header.

I.E:
gzip on;
.
.
.
location /foo/bar {
proxy_pass http://server:123;

if ($upstream_http_etag) {
gzip off;
}
}

Basically I'm looking for a workaround to this bug that will disable the gzip compression if server responded with etag header.

http://trac.nginx.org/nginx/ticket/377

Thank you,
Vitaly