Proxy: fixed proxy_set_body with proxy_cache. If the last header evaluation resulted in an empty header, the e.skip flag was set and was not reset when we've switched to evaluation of body_values. This incorrectly resulted in body values being skipped instead of producing some correct body as set by proxy_set_body. Fix is to properly reset the e.skip flag. As the problem only appeared if the last potentially non-empty header happened to be empty, it only manifested itself if proxy_set_body was used with proxy_cache.

--- a/src/http/modules/ngx_http_proxy_module.c
+++ b/src/http/modules/ngx_http_proxy_module.c
@@ -1379,6 +1379,7 @@ ngx_http_proxy_create_request(ngx_http_r
     if (plcf->body_values) {
         e.ip = plcf->body_values->elts;
         e.pos = b->last;
+        e.skip = 0;
 
         while (*(uintptr_t *) e.ip) {
             code = *(ngx_http_script_code_pt *) e.ip;