id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	uname	nginx_version
922	"proxy_cache use wrong file name, if set on backend ""gzip on""."	lefoyer@…		"proxy_cache use wrong file name (first request from firefox=md5(proxy_key), second request  from chrome != md5(proxy_key)), if set on backend ""gzip on"".

I am reproduse this bug on nginx 1.8.1

For reproduce:
/etc/nginx# cat nginx.conf
user www-data;


pid /run/nginx.pid;

events {
        worker_connections 786;
}

http {

        proxy_cache_path  /var/cache/fscache/ngcache levels=1:2 keys_zone=fastcache:40m inactive=7d max_size=600g use_temp_path=off;
        proxy_cache_min_uses 1;
        proxy_cache_methods GET HEAD;
        proxy_http_version 1.1;

        include /etc/nginx/mime.types;
        default_type application/octet-stream;

        ssl off;

        access_log /var/log/nginx/access.log;
        error_log /var/log/nginx/error.log;

        gzip on;
        gzip_disable ""msie6"";

        gzip_vary on;
        gzip_proxied any;
        gzip_comp_level 6;
        gzip_buffers 16 8k;
        gzip_http_version 1.1;
        gzip_types text/plain text/css application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript image/svg+xml;

    server {
        listen 127.0.0.1:80;
        server_name     test.local *.test.local;

        root /var/www/html;
        index index.html index.htm;

        location / {
            try_files $uri $uri/ =404;
        }
    }

    server {
        listen 80;
        server_name     test.local *.test.local;

        root /var/www/html;
        index index.html index.htm;

        location / {
            proxy_pass  http://127.0.0.1:80/;
            proxy_cache fastcache;
            proxy_cache_key $request_method|$host|$uri;
            proxy_cache_valid 200 15m;
            proxy_set_header Host $http_host;
        }
    }


}


/var/www/html/test# cat test.css
table.programm-table {
        margin: 0 0 35px !important;
}

table.programm-table {

}

table.programm-table tbody tr {
        background: #F9F9F9;
}

table.programm-table tbody tr td input,
table.programm-table tbody tr td select {
        width: 100%;
}

#plupload-upload-ui .in-progress {
        display: none;
}

#plupload-upload-ui.in-progress .can-upload {
        display: none;
}

#plupload-upload-ui.in-progress .in-progress {
        display: block;
}

#xml-programm-posts,
#xml-programms-list {
        margin: 40px 0 0;
}

.xml-posts h2 {
        padding: 10px !important;
        background: #F9F9F9;
        border: 1px solid #e5e5e5;
        -webkit-box-shadow: 0 -1px 1px rgba(0,0,0,.04);
        box-shadow: 0 -1px 1px rgba(0,0,0,.04);
        border-bottom: none;
}


write in host test.local you wan server ip.

Request http://test.local/test/test.css from Firefox and Chrome.

My result in attach (2 file).
 


"	defect	closed	minor		nginx-module	1.9.x	invalid	proxy_cache	admin@…	Linux hw-sld-prod-front-001 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt20-1+deb8u3 (2016-01-17) x86_64 GNU/Linux	"nginx version: nginx/1.9.10
built with OpenSSL 1.0.1k 8 Jan 2015
TLS SNI support enabled
configure arguments: --with-cc-opt='-g -O2 -fPIE -fstack-protector-strong -Wformat -Werror=format-security -D_FORTIFY_SOURCE=2' --with-ld-opt='-fPIE -pie -Wl,-z,relro -Wl,-z,now' --prefix=/usr/share/nginx --conf-path=/etc/nginx/nginx.conf --http-log-path=/var/log/nginx/access.log --error-log-path=/var/log/nginx/error.log --lock-path=/var/lock/nginx.lock --pid-path=/run/nginx.pid --http-client-body-temp-path=/var/lib/nginx/body --http-fastcgi-temp-path=/var/lib/nginx/fastcgi --http-proxy-temp-path=/var/lib/nginx/proxy --http-scgi-temp-path=/var/lib/nginx/scgi --http-uwsgi-temp-path=/var/lib/nginx/uwsgi --with-debug --with-pcre-jit --with-ipv6 --with-http_ssl_module --with-http_stub_status_module --with-http_realip_module --with-http_auth_request_module --with-http_addition_module --with-http_dav_module --with-http_flv_module --with-http_geoip_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_image_filter_module --with-http_mp4_module --with-http_perl_module --with-http_random_index_module --with-http_secure_link_module --with-http_v2_module --with-http_sub_module --with-http_xslt_module --with-mail --with-mail_ssl_module --with-stream --with-stream_ssl_module --with-threads --add-module=/build/nginx-1.9.10/debian/modules/headers-more-nginx-module --add-module=/build/nginx-1.9.10/debian/modules/nginx-auth-pam --add-module=/build/nginx-1.9.10/debian/modules/nginx-cache-purge --add-module=/build/nginx-1.9.10/debian/modules/nginx-dav-ext-module --add-module=/build/nginx-1.9.10/debian/modules/nginx-development-kit --add-module=/build/nginx-1.9.10/debian/modules/nginx-echo --add-module=/build/nginx-1.9.10/debian/modules/ngx-fancyindex --add-module=/build/nginx-1.9.10/debian/modules/nginx-http-push --add-module=/build/nginx-1.9.10/debian/modules/nginx-lua --add-module=/build/nginx-1.9.10/debian/modules/nginx-upload-progress --add-module=/build/nginx-1.9.10/debian/modules/nginx-upstream-fair --add-module=/build/nginx-1.9.10/debian/modules/ngx_http_substitutions_filter_module
"