src/http/ngx_http_upstream.c:3475: error: Integer Overflow L2
  ([0, +oo] - 1):unsigned32 by call to `ngx_http_file_cache_free`.

src/http/ngx_http_upstream.c:3475:17: Call
3473. 
3474.             } else if (p->upstream_error) {
3475.                 ngx_http_file_cache_free(r->cache, p->temp_file);
                      ^
3476.             }
3477.         }

src/http/ngx_http_file_cache.c:1494:1: <LHS trace>
1492. 
1493. 
1494. void
      ^
1495. ngx_http_file_cache_free(ngx_http_cache_t *c, ngx_temp_file_t *tf)
1496. {

src/http/ngx_http_file_cache.c:1494:1: Parameter `c->node->count`
  1492. 
  1493. 
  1494. void
        ^
  1495. ngx_http_file_cache_free(ngx_http_cache_t *c, ngx_temp_file_t *tf)
  1496. {

src/http/ngx_http_file_cache.c:1512:5: Binary operation: ([0, +oo] - 1):unsigned32 by call to `ngx_http_file_cache_free` 
  1510. 
  1511.     fcn = c->node;
  1512.     fcn->count--;
            ^
  1513. 
  1514.     if (c->updating && fcn->lock_time == c->lock_time) {
