about get etag from r->upstream.headers_in->etag

[bit bull]

hi, all:

       sorry for my pool english. I write a filter, it need get
etag(http header) from proxied server. But I cant get etag in
r->upstream.headers_in->etag, so I added

"#if (NGX_HTTP_MYMODULE)
    { ngx_string("ETag"),
                 ngx_http_upstream_process_header_line, 1,
                 ngx_http_upstream_copy_header_line
                 offsetof(ngx_http_headers_out_t, etag), 1 },
#endif
"

to ngx_http_upstream.c:ngx_http_upstream_headers_in[].


         It's work. but I worry about it will make some bugs, because
I dont know why nginx not supported this.

         who can tell me something about this or nginx will supported
this in future?

        thanks very much.

wengjy