src/http/ngx_http_upstream.c:2708: error: Integer Overflow L2
  ([0, +oo] - 1):unsigned32 by call to `ngx_http_file_cache_free`.

src/http/ngx_http_upstream.c:2708:21: Call
2706. 
2707.                 } else {
2708.                     ngx_http_file_cache_free(r->cache, tf);
                          ^
2709.                 }
2710. 

src/http/ngx_http_file_cache.c:896:1: <LHS trace>
894. 
895. 
896. void
     ^
897. ngx_http_file_cache_free(ngx_http_cache_t *c, ngx_temp_file_t *tf)
898. {

src/http/ngx_http_file_cache.c:896:1: Parameter `c->node->count`
  894. 
  895. 
  896. void
       ^
  897. ngx_http_file_cache_free(ngx_http_cache_t *c, ngx_temp_file_t *tf)
  898. {

src/http/ngx_http_file_cache.c:914:5: Binary operation: ([0, +oo] - 1):unsigned32 by call to `ngx_http_file_cache_free` 
  912. 
  913.     fcn = c->node;
  914.     fcn->count--;
           ^
  915. 
  916.     if (c->updating) {
